This post began as a paper I gave at the Annual Association for Medical Humanities Conference, University of Aberdeen, 8th – 10th July 2013. I have posted a review of the conference here.
Dangerous, difficult births
Explanations for the biological origins of twins during the Middle Ages realigned the ancient emphasis on the causal strength and quantity of male seed to include the moral behaviour of individuals, the internal environment experienced by fetuses, and the damaging effects of twin pregnancy. In a very general sense, biological explanations of twinning authored by male philosophers and theologians stressed understandings of sex and gender that gave women a much greater responsibility for the formation and fate of twins. This is partly explained by a greater focus on the female body. Gynecological tracts sought to understand how and why twins caused pregnant women such difficulty. Concerns about the dangers of multiple birth have their roots in ancient medical texts and are well documented in the long history of translations and reproductions produced in the Middle Ages; they can now be viewed as a visual record for how the phenomenon of twinning was explained and imagined in utero. Gynecological tracts were frequently illustrated, exposing the uterus by cross-section, the womb a vessel disembodied from its surrounding organism, a globular space in which the maternal relation is made wholly material. A good example of this visual as well as epistemological technique can be found in this ninth century image (Fig. 1). Reflecting the extended temporal, intertextual and international genealogy of the gynecological knowledge of the Middle Ages, this image has been adapted to illustrate a text composed sometime between the fifth and sixth century AD. It represents a means to visualise the unseen dangers associated with multiple conceptions, to focus on and isolate the presentation of different kinds of twin and higher-order multiples in the uterus. As an image that shows the confluence of content, taken from many separate sources, and epistemology, that depended upon a decorative yet anatomically disembodied style of illustration, the result is curious and rather gargantuan entanglement of multiple neonates, caught, twisted and entwined together.
There are various intertexts for these interuterine views, the most familiar to pious northern Europeans may have been the story of Jacob and Esau: scriptural twins who are said to have ‘struggled together’ in Rebekah’s womb (Gen 25:22). The sight of one twin with a hand clasping the other’s ankle in the next image (Fig. 2) – much like how Jacob is described to have had ‘his hand took hold on Esau’s heel’ (Gen 25: 26) compounds the dramatic and foreboding sense that interuterine conflict prefigures later difficulties or struggles, especially in monotheistic cultures dominated by systems of primogeniture; the simultaneity of twin birth may cause lifelong discord. But while the struggle between Jacob and Esau foretold a greater conflict, medieval medical texts tended to stress the material and physical reasons for why a woman might experience difficulty in labour.
These fetal views, sometimes detached and circulated free from their accompanying texts, were widely distributed across Europe during thirteenth and fourteenth centuries. Fig 2 was heavily influenced by those that appeared in earlier writings of Soranus, it had a profound and long-lasting influence on how medieval and early modern writers imagined twin pregnancies. As Monica Green has shown, Soranus was an especially important source for Eucharius Rösslin and his Der Rosengarten (The Rose Garden, 1513). This text, Green shows, was vital for the professionalization, standardization, and internationalisation of midwifery. Der Rosengarten became a bestseller in the field, was widely disseminated when published in the early sixteenth century, and went through sixteen editions in its original form, revised into three different German versions (each of which went through multiple printings), translated into Czech, Danish, Dutch, English, French, Italian, Latin, and Spanish. Rosslin’s was, in this sense, an internationalised text that addressed a global health issue. Most fundamental from our point of view was his reliance on and assistance of these globular and disembodied wombs that can be traced back to Soranus; rugged-cheeked twin homunculi, who in position and presentation carry some visual likeness of their 9th century compatriots. In effect, the twin child is motherless; every emphasis is placed on the position of the twin vis-à-vis the other twin.
But in reading these guides and manuals as a purely visual record neglects their purpose in illustrating the experience ‘difficult birth’ and the help they offer to midwives in mitigating the severe risk of such births. Immersed in this longer tradition that places twins in a category of ‘difficult births’ one fourteenth-century Hebrew writer would define the birth of twins as similar in kind to when,
the foetus is dead, or when his head is very big, or when he has two heads, or when there are / twins, or when the birth is unnatural, or when it occurs before time, or when the woman is very old, or as a result of the uterus’ diseases [etc]
The structural nature of this litany is telling, precisely for where twins are inserted – ‘when his head is very big, or when he has two heads, or when there are / twins, or when the birth is unnatural.’ Again, there exists taxonomic proximity between twin births and physical mutation and pathology, ultimately situating twins in the realm of sickness and physical dysfunction. Similarly, in an early fifteenth-century obstetric text known as the ‘Trotula Manuscript’ (Sloane MS 2463), the earliest obstetric work in Middle English, twins are categorized as a ‘vnkyndely’ or ‘unnatural.’ When delivering twins a midwife is instructed to put:
aye noon with hyr fyngers the whiles she hathe forth oon of þe children. And þan after, another, do doing þat þe moder be noȝt repressed, þe children mysfaren with all, as it fareth often tyme.
[one back again with her fingers while she brings out one of the children. And then afterward, another, so doing that the uterus is not constricted nor the children brought to grief, as often happens.
The advice given here provides a small insight into the challenges faced by mothers and midwives. Elsewhere in this handbook a constricted uterus is said to cause blood retention, the build up of ‘corrupt and venomous uterine humors,’ feverishness and fainting. The risks are not only multiple but predictably malignant, unless difficult interventions are not made. The humoural basis of health, which stressed the balance of composite corporeal humours, dominated Northern European medical thought throughout the Middle Ages and early modern periods. Medieval writers taught how well-being was guided by a balance of four humours: colic, phlegm, black bile and blood. To remain healthy was to keep these humours in equilibrium and a temporary imbalance could lead an individual to experience sickness or disease. Giving added visual support to this traffic between twins and sickness, the image below (Fig. 3) shows a figura infirmitatum, a pedagogical device used by teachers of anatomy and medicine to present the locations of different illnesses and diseases said to afflict the human body. Dating from the early fourteenth century, it shows a woman’s body displayed with its many possible pathologies: tumours, swollen feet, and skin conditions. Perhaps the more unexpected of these appears at each side of her abdomen, two isolated twins in separate pockets.
The emphasis on balance, proportion, and equilibrium was influential in determining how twins were generated. The reason why twins in this image are far apart may lie in the theory that twins were caused by the divided structure of a woman’s uterus. This not only has a bearing over how twins relate to the overall health of the mother but also how the birth of twins reflected her sexuality, morality, and thus her social reputation.
Sex and desire
For Galen, the influential Greek philosopher and doctor, a woman’s uterus has two sinuses in proportion to the number of children she is capable of conceiving. His argument was based on the belief that all animals give birth to the number of offspring they are able to rear: ‘just as the whole body is double with right and left sides, so too there is one sinus placed in the right part of the uterus and another in the left […] all other animals too always bear the same number of foetuses as they have teats.’ Hence, Galen believed that the uterus has two cells, and that each side was responsible for forming the gender of a child with females developing to the left and males to the right. In the writings of Salernus this ancient belief was extended to seven chambers, to account for multiple births of higher numbers, and remained popular well into the late Middle Ages. The doctrine of the seven-cell uterus in its completed form was adopted by anatomists at Salerno, the prominent anatomists of Bologna, and those that visited these centers of anatomical thought such as Michael Scotus (1175 – c. 1232) and Mondino de Luzzi (c. 1270 – 1326). A mechanistic theory was established that could explain the different kinds of birth according to the foetuses’ place of development, with three chambers on the left for females and three to right for the males, and another in the middle of the others where it was through that hermaphrodites were formed.
Debates about how twins were generated as a distinct capacity of a woman’s anatomy not only cast the biological responsibility of twinning upon her ‘natural’ capacities but it also made the origin of twins a woman’s secret. It is not surprising, then, to find beliefs about the seven-celled uterus, whose origins can be placed in the Galenic tradition but whose influence developed over subsequent centuries, appear in popular court poetry. This extract from a fourteenth-century poem, translated from French by Hugh of Caumpeden in the 1530s, sees the literary and philosophical converge in a single text:
May any woman bear mo
Children in her at once but two?
A woman may ber kindly
Seven at once in her body,
For the matrice of woman,
If that thou understand can,
Hath seven chambers and no mo,
And each is departed other fro,
And she may have in each of tho
A child and with seven go,
If God’s will be first thereto
And the kind of woman also.
If hot of kind be the woman
And great liking hath to man,
One chamber or two or three
Of thilike that in matrice be
Of great will open there again
When that a man hath by her lain.
Hugh’s text describes the anatomical structure of a woman and the dynamic relationship with her ‘great liking’, her sexual appetite. Adopting the language of Galen, Hugh understands women to be naturally colder than their male counterparts. To be ‘hot of kind’ made higher order multiples more likely and twins, then, a minimal measure of enlarged sexual and reproductive potential.
The fusion of ancient natural philosophy and medieval moralism is especially evident in the writings of the thirteenth-century theologian, Albert the Great (Albertus Magnus, c. 1200 – 1280). Though Albert did not fully endorse the Hippocratic and Galenic view that the shape of a woman’s uterus was the cause of twins,  he did regard multiple birth as a sign that humans were liminal figures whose sexual appetites could encourage the generation of multiples: ‘the human is an animal lying midway, as it were, between two genus, one of which naturally generates many young and the other which naturally generates one young.’ As a consequence, twins are drawn into debates not only about the animality of humans but also included in more general discussions about the meaning and significance of mutants and monsters. So, in Book 18 of On Animals, his commentary on Aristotle, we find a monk like Albert suggesting that the ‘cause of too many or too few members being one and the same.’ Albert also agrees with Aristotle’s theory of seed but recognises that men and women make an equal contribution to the formation of a fertilised embryo (‘the male produces excessive sperm and the female with whom he copulates should overbound as well with a great deal of superfluity’). Hence, for Albert, twins exist on a cline of the monstrous that links multiple births to physical deformation and sexual ambiguity: ‘if the power in one is overcome and overcomes in the others, then a hermaphrodite will be generated.’ Next to these Aristotelian ideas, however, which are largely material and teleological in nature, Albert added the vagaries of a woman’s sexual pleasure, which he also thought to be equally and problematically given to excess.
The cause of Albert’s revision of Aristotle may reflect lie in the sources that were not of Greek or Roman origin. J. M. Thijssen argues that his writings bear a strong resemblance to those of the tenth-century Persian philosopher and medic, Avicenna (980 – 1037), particularly where he mimics Avicenna’s understanding of twin birth and its departure from more mechanistic theories. Via Avicenna, Albert stresses the emotional content of human reproduction and the way that the pleasure and heat that women may feel during sexual intercourse makes a significant contribution to the generation of twins. This pleasure is said to occur in three stages, at the moment of female ejaculation (eiectiones spermatis), the movements of the vulva when it draws in semen (Mootus orificii matricis in sugendo), and the movements of the womb throughout pregnancy. The various kinds of pleasure women may feel during and after intercourse, especially where it may encourage movement, thought Albert, served to harness and redistribute the overabundant quantity and position of sperma, causing it to divide and settle into the different parts of her uterus to generate twins. Such twin-making pleasures reinforced Albert’s belief that women were, when compared to other animals, sexually insatiable; indeed, the generation of twins could be used as evidence for their sexual appetites.
Above all other animals, Albert claims, female humans and mares are most likely to superfecundate; to conceive in separate but sequential copulations and generate twins in a single gestation. Whereas Aristotle presented superfecundation as a rare event and could allude to the mythology familiar to his interlocutors, Albert makes it an active extension of female desire because she ‘desire[s] copulation more than do others. It is the toughness of their flesh which creates (or rather gives indication of) this appetite. All animals which have tough flesh have full flesh because blood does not flow out from them and the last food is poured into the members. They thus desire a great deal of copulation, especially woman and the mare.’ It is not simply the case that women can emit a material excess of ‘spermatic humor,’ they are naturally predisposed towards a expressing an increased sexual appetite. Twins, as the gendered by-product of an immanent bodily and moral predisposition, were taken as evidence of how material and ethical taxonomies could coalesce in the natural world.
Assessments of twins that stress the sexual behaviour of women cast the ‘issue’ of twins – both as a process that resulted in birth and as figures of scholastic debate – into a wide variety ancillary debates: the anatomical composition of human sexuality and gender; the domestic roles of each gender; ideals about the size and composition of populations; the paths for Christian salvation. For women, the bearing of children during this era was seen as both a punishment for the original sin of Eve and a means to attain salvation. So, a contemporary Dominican to Albert, Nicholas of Gorran (1232 – 1295), argued that a woman’s source of Christian salvation was to ‘generate children continually until her death.’ While such attitudes towards childbirth do not tend to mention twins explicitly, moral economies that determined gender roles on the basis of reproductive capacity may have encouraged parents of twins to view their offspring as an extension of their religious duty. On this I can only speculate. Where twins are mentioned in Albert’s writings we find him taking a more cautious view – both towards multiple births and towards human population growth more generally. He acknowledges that salvation-through-reproduction, if pursued, harboured the threat of overproduction. We see then, in this illuminated manuscript of de Animalibus, a continuum; from single pregnancy at the top, to twin pregnancy directly below, to the woman at the bottom corner with quintuplets, to the figure in the right margin, whose gargantuan reproductive capacities render her pregnant with 28 foetuses. Though his text stresses that such outcomes are unlikely, the causal mechanism and the depth of female desire described within makes this threat possible
The agency that Albert adds to his traditional Aristotelian view, particularly his stress on the sexual pleasures of women, makes twins a threatening sign of humankind’s fallen animality, imperfection, and sinfulness. This is why twins were absorbed into categories of monstrosity that, following Aristotle, placed them alongside those born with extra digits, limbs, and so on. But, as Robert Olsen and Karen Olsen observe, medieval commentators looked to account between physical and moral monstrosities: ‘what constitutes a monster involved more than just physical appearance (‘physical monstrosity’); instead, physical differences were also associated with aberrant ethical behaviour (‘moral monstrosity’) and exotic ethnical customs.’ Twins, as a consequence, were recruited into scholastic debates as evidence and as omen; proof of parental and moral error.
Suggested in Fig.4 is the greater anxiety that multiple birth marks a descent into monstrous abundance and the generation of an unsupportable multitude, an imbalance at the level of the collective to match that of the individual. Albert is a surprising advocate of abortion as a means of controlling population levels: ‘he who strikes a pregnant woman [in a way] which brings about abortion of a not yet formed foetus, that is, [not yet] born [sic], should not be guilty of homicides.’ From a broader perspective, we can only guess at how high mortality rates were both for mothers of multiple birth and their offspring. Latin writers were unequivocal on this matter, ‘when twins are born,’ writes Pliny the Elder (23 – 79AD), ‘it is rare for the mother or more than one baby to live.’ It was even more risky to have twins of mixed sex, with the female viewed as more vulnerable and more likely to suffer and die. As Robert Wood argues in Death Before Birth, infant and early-neonatal mortality rates, as well as the frequency of still- or ‘deadborn’ children were significantly higher than they are today. Despite the great problems associated with calculating mortality rates for periods when methods of record keeping and standards of categorisation were both inconsistent and incomplete,Woods goes to great lengths to substantiate his claim that singleborn infant and maternal death rates were at least three times higher prior to 1550. From this we return to where this inquiry began – difficulty and mortality. Twin pregnancies, with their added risk of a great range of developmental, nutritional and obstetric risks, as well as low birth weight and increased rates of premature delivery, were considered to be even more hazardous; having and being twins in this period was fraught with both moral and mortal risk, permitting those that sought to categorise and measure those risks to use the birth of twins as emblematic bodies of evidence.
Adultery and exposure
Suppose that you found yourself in a rare minority who, having run the gauntlet of twin delivery, its associations with sickness and monstrosity, manage to survive and see your children live. How did society view you as a mother of twins? What status was given to or adopted by twins? Here the historical record is scant and the information available compromised by the genre or intention of the work. What we do have are an enormous number of twins in folk tales and ballads, court poetry and prose. To what extent we should take this imaginative literature as a form of historical documentation is fraught with problems that are familiar to literary and cultural historians. These literatures are complex objects serving multiple purposes, the least of which may be to hold up a simple, mimetic, documentary relationship with the social affairs they express. Leaving aside the matter of whether or not medieval literature’s representations of twins reflect the beliefs of those that wrote, read or listened to them, the overall patterns and repetitions are instructive for the way they corroborate certain historic attitudes or atmospheres that were explored in earlier parts of this chapter. For the principle treatment of twins in this literature is of exposure; the public manifestation of hidden or forbidden acts. Hence, it is rare for the birth of twins in these stories to provide a simple occasion for celebration. Instead, twin birth is again the trigger for moral scrutiny and a means by which narratives can afford opportunities to expose the proper conduct of individuals.
The birth of twins in the literary art of the Middle Ages frequently marks an opportunity for one woman to accuse another of adultery and thus the twins as illegitimate. Erik Kooper has analysed twenty European stories, many of which were translated, redacted and adapted, and he divided these according to the way in which twinship is represented. ‘If one thing becomes clear from this kind of classification,’ Kooper concludes, ‘is that multiple births do indeed lead to numerous kinds of disaster, both for the mother and for the children.’ Of the twenty or so he lists, only four of these stories leave mother or child protagonists untainted by accusations of adultery or monstrous birth. In stories that are free of these kinds of accusation, like the late twelfth-century French story Aiol whose royal twins are born in a prison and later exposed, twins are by no means free of other kinds of peril. Similarly, in the early fifteenth-century romance, Sir Torrent of Portyngale, the eponymous hero is separated from his twin sons without negative judgement being attached to the phenomenon of twinning, but that does not mean that its twin protagonists are straightforwardly celebrated either. The stories benefit from the narrative pathos and closure forged through the eventual reunion of parents children: extending and complicating the romance drama of ‘setting out’; incorporating, in both senses, multiple protagonists. These twin stories, however, form a minority. Many others involve an accusation of adultery and/or animal birth, the threat of such accusations, and the retribution served by the religious and civic orders that these accusations threaten to disrupt.
One of the most famous narratives in which the mother of twins is accused of adultery is found in Marie de France’s short romance, Lai Le Fresne. It is one of Marie’s shortest lays, written in French some time in the late twelfth century, and it bares close similarities to ballads such as ‘The Man With Two Wives’ and ‘Fair Annie.’ Marie’s story begins with the birth of twin sons to one noble woman. A jealous neighbour claims that the twins are not the sons of her husband but that the noble woman has, in fact, had sex with two men:
Ich have wonder, thou messanger,
Who was thi lordes conseiler,
To teche him about to send
And telle schame in ich an ende,
That his wiif hath to childer ybore.
Wele may ich man wite therfore
That tuay men hir han hadde in bour;
That is hir bothe deshonour. (65–72).
The poem matches contemporary theses advanced by natural philosophers and theologians, such as Albert, who argued that superfecundation, female sexual proclivity, and the generation of twins were all entwined. Note that in Marie’s story the twins are treated as the sole evidence of an adulterous act: it is not supplemented by any other kind of visual, verbal or written proof. Shortly after making this accusation the nameless woman who accuses her neighbour then conceives twin daughters of her own; she is therefore incriminated by her earlier accusation. Not only does this disrupt the moral polarity between accused and accuser, it also contravenes the major conventions of romantic literatures, epitomised by figures such as Guenevere and Iseut, which tended to amplify acts of adultery with threats of infertility. In a complex way, the issue of twins as a result of an adulterous union compromises the gendered, political, religious, and literary conventions of the period; its narrative impact is to suspend a damaging doubt over who is the rightful father and legitimate heir.
Multiple birth – a taboo that inspires accusation, punishment, and abandonment – also seems to displace the incest taboo that frequently motivates infant exposure in stories about male foundlings. Hence, the accusing noble woman in Marie’s lai, now pregnant with her own twins, seeks to protect herself and the reputation of her offspring. First she considers killing one of her daughters – a reflection of how exposure was a response to unwanted births during this period – but then gives one infant child to a servant who takes and hangs it in an ash tree, wrapped in an expensive cloth and with her mother’s ring. She leaves the child in the grounds of a convent and it is by this ash tree, le frêne in Old French and frein in Middle English. Named after the tree in which she was found, Frein is raised and educated by the abbess’ niece and later falls in love with a wealthy knight called Guroun. But the knight is persuaded to marry someone rich and have legitimate children. Without realising the family connection the knight decides to marry Frein’s twin sister. Frein, though sorry for her loss, graciously adorns the matrimonial bed with the cloth in which she was abandoned and, when this garment is recognised by her mother, she also produces the ring and explains how they came into her possession. Her sister’s marriage is quickly annulled and Frein marries Guroun. Frein’s twin is married to a suitably wealthy knight and, despite the years that have passed, order is restored.
To the turbulent plot of Frein we can add Octavian, a popular family romance throughout the fourteenth century, initially composed in Old French and then abbreviated into two Middle English versions. In this story, the Emperor Octavian and his Empress seek an heir – there are concerns that the Empress may be infertile – and so they build an abbey in the hope that their piety may bring them divine favour. Their prayers are answered in the shape of twin sons. In this respect, their children have divine connotations; a sign of divine intervention and a resolution to anxieties surrounding royal succession: ‘An abbaye than he gerte wyrke so / And sone he gatt knave chidire two, / Als it was Goddis will’ (82–84), In a way which corroborates the notion that twin births are difficult and painful, the text stresses the physical exertion and exhaustion of twin delivery: ‘Full grete scho wexe with paynnes sore’ (86). Further difficulties arise when the Empress’ mother-in-law claims that the twins fathered by the cook’s assistant and the Emperor exiles wife and children. The family undergo further separation when each twin is abducted, the first by an ape and the second by a lioness. After further abductions, adoptions, giant killings, battles and romantic conquests, displays of taste and indications of their innate nobility, the adult children are restored to their parents. At the point of reunion, ‘full joye there was also / At the metyng of the brethir two’ (1898–1899). In a fashion that seems to stress the dramatic capacity of twinning rather than any intrinsic or absolute quality unique to twins, their ‘true’ identity is revealed by their actions; through their valour at court and on the battlefield. The deceitful mother-in-law, now threatened by her husband to death by fire, takes her own life. According to literary convention, order and peace are restored.
As much as it is important to stress a continuity between works of natural philosophy, medicine, and literature in the Middle Ages, which all in their different ways highlight how twinship was viewed as a fundamentally disruptive event – a woman’s natural and spiritual burden – it is also essential to identify the drama and entertainment afforded by the birth of twins; twins are catalysts for demarcating the orderly from the disorderly, the usual and the unusual, the desired and the undesirable. This optical and instrumental quality of twinning is not specific to this period of human history. Though what is viewed, calibrated, or measured may change, the inclusion of twins as evidence for the orders and aberrations of nature is a persistent aspect of human self-assessment. The category of ‘twin’ is unusual, therefore, since it is not simply defined by authorities who build upon one another’s knowledge in an accumulative fashion, but twins gain their transhistorical meaning from the many different and divergent kinds of authority that is achieved using their bodies.
 Muscio’s Gynaecia, an interpretation of Soranus’ Gynecology, trans. Owsei Temkin (Baltimore, MD: Johns Hopkins University Press, 1956), p. xlv. The specific details of Muscio’s life are unknown but it is generally held that he translated the text in North Africa in the fifth or sixth century. See Monica H. Green, ‘From ‘Diseases of Women’ to “Secrets of Women”: The Transformation of Gynecological Literature in the Later Middle Ages,’ Journal of Medieval and Early Modern Studies, 30 (2000): p. 8 [pp. 5–40].
 See Monica H Green, Making Women’s Medicine Masculine: The Rise of Male Authority in Pre-Modern Gynaecology (Oxford: Oxford University Press, 2008).
 Monica H. Green, ‘The Sources of Eucharius Rösslin’s ‘Rosegarden for Pregnant Women and Midwives’ (1513),’ Medical History 53(2) (2009): 167–192.
 Anon, ‘On Difficulties of Birth,’ translated by Ron Barkai, Paris Bibliotheque Nationale, Ms. heb. 1120 ff. 66v.-67r.
Medieval Woman’s Guide to Health: The First Gynecological Handbook, edited by Beryl Rowland (Croom Helm: London, 1981), p. 133
Medieval Woman’s Guide to Health, p. 134, p. 135.
 Ibid, p. 87.
 See Joan Cadden, The Meanings of Sex Difference in the Middle Ages: Medicine, Science, and Culture (Cambridge: CUP, 1993), p. 35
 Galen, On the Usefulness of the Parts of the Body: De usu partium, 2 vols, translated by Margret Tallmadge May (Ithica, NY: Cornell University Press, 1968), II. 625.
 Fridolf Kudlien, ‘The Seven Cells of the Uterus: The Doctrine and its Roots,’ Bulletin of the History of Medicine 39:5 (1965), 415–423
 Edward Reichman, ‘Anatomy and the Doctrine of the Seven-Chamber Uterus in Rabbinic Literature,’ Hakirah 9 (2010), p. 249. [245-265]
 Hugh of Caumpeden, Landsdowne mss 793, British Museum, London.
 Albertus Magnus, On Animals: A Medieval Summa Zoologica, vol 2, translated and annotated by Kenneth F. Kitchell Jr. and Ireven Michael Resnick (Baltimore, MD: John Hopkins University Press, 1999), II.1309; 18.58.
 Albertus Magnus, On Animals, II.1311; 18.63
 Albertus Magnus, On Animals, II.1314; 18; 69.
 Ibid, I.1311; 18.62.
 Ibid, II.1313; 18.66.
 Ibid, I.825; 9.132–133. Here I have also been guided by the summary offered by J. M. Thijssen in his ‘Twins as Monsters: Albertus Magnus’s Theory of the Generation of Twins and its Philosophical Context , Bulletin of the History of Medicine, 61, 2 (1987), 246. [pp. 237–246].
 Albert, On Animals, II.1315; 18.71. II.1316.18.72
 See Angela M. Lucas, Women in the Middle Ages: Religion, Marriage and Letters (Brighton: Harvester, 1982), p.18.
 Quoted in R.C. Finucane, The Rescue of the Innocents: Endangered Children in Medieval Miracles (London: Macmillan, 1997), p. 18.
 K. E. Olsen and L. A J. R. Houwen, ‘Introduction’, Monsters and the Monstrous in Medieval Northwest Europe (Leuven: Peeters, 2001), p. 8 [pp.1–22].
 Quoted in Peter Biller, the Measure of Multitude: Population in Medieval Thought (Oxford: OUP, 2000), p. 368.
 Pliny the Elder, Natural History: Book 7, translated by Mary Beagon (Oxford: Oxford University Press, 2005), p. 67.
 Indeed, so common was the death of at least one twin during pregnancy, that the ancient Romans named ‘Vopiscus’ the surviving twin. See Pliny the Elder, Natural History, p. 69.
 Robert Wood, Death before Birth: Fetal Health and Mortality in Historical Perspective (Oxford: OUP, 2009), pp. 96–98.
 See Erik Kooper, ‘Multiple Births and Multiple Disaster: Twins in Medieval Literature,’ in Conjunctures: Medieval Studies in Honor of Douglas Kelly
- Douglas Kelly, Keith Busby and Norris J. Lacy (Amsterdam: Rodolpi, 1994), pp. 256–260.
 Kooper, ‘Multiple Births and Multiple Disaster,’ p. 260.
 The extent to which Marie de France’s Lai le Freine is a ‘romance’ in a generic and critical sense is discussed by Elizabeth Archibald, see ‘Lai le Freine: The Female Foundling and the Problem of Romance Genre,’ in The Spriit of Medieval English Popular Romance, edited by Ad Putter and Jane Gilbert (Harlow: Longman, 2000), pp. 39–55.
 See Francis J. Child, The English and Scottish Popular Ballads, vol.2 (Boston: Houghton, Mifflin and Co. 1883-86), II.63–83, and Erik Kooper, ‘Multiple Births and Multiple Disaster: Twins in Medieval Literature,’ pp. 253–270.
 All quotes from Marie de France, Lay le Freine, in The Middle English Breton Lays, Edited by Anne Laskaya and Eve Salisbury (Kalamazoo, MI: Medieval Institute Publications, 1995), pp. 65–74.
 See Peggy McCraken, ‘The Body Politic and the Queen’s Adulterous Body in French Romance,’ in Feminist Approaches to the Body in Medieval Literature, edited by Linda Lomperis and Sarah Stanbury (Philadelphia, PA: Pennsylvania University Press, 1993), pp. 29–64.
 See Elizabeth Archibald, Incest and the Medieval Imagination (Oxford: Oxford University Press, 2001).
 John Boswell details the history of child abandonment in the Middle Ages; he writes that ‘between 1195 and 1295 at least thirteen different councils in England alone passed legislation directly or indirectly bearing on the abandonment of children’, see The Kindness of Strangers (New York: Vintage, 1990), p. 322.
 On medieval theories of resemblance see Paul Vincent Rockwell, ‘Twin Mysteries: Ceci n’est pas un Fresne,’ in Conjunctures: Medieval Studies in Honor of Douglas Kelly, pp. 487–504.
 See Harriet Hudson, ‘Octavian: Introduction,’ in Four Middle English Romances: Sir Isumbras, Octavian, Sir Eglamour of Artois, Sir Tyramour, edited by Harriet Hudson (Kalamazoo, MI: The Consortium for the Teaching of Middle Ages, 1996), pp. 45–52.
 Citations are to Harriet Hudson’s edition of the Northern, Thornton version, Four Middle English Romances, pp. 53–114. Line numbers are given in parentheses in the main body of the text.