Support First Things by turning your adblocker off or by making a  donation. Thanks!

Teaching Dante’s Divine Comedy last semester, I hoped to cruise through the Purgatorio to make sure we completed the Paradiso by semester’s end. But my students wouldn’t let me skip canto 25—they stopped there, awestruck. I think we spent longer in the seventh cornice on the mount of purgatory than Dante did.

There Statius explains to Dante the generation of the embryo, and how the embryo passes through various stages before it can be considered a rational human: “This active power,” reads Robert M. Durling’s translation, “having become a soul like that of a plant, but different in so far as it is still under way, while the other is already in port,”

next works until it moves and has feeling like a sea sponge, and then it undertakes to shape organs for the faculties of which it is the seed
. . . as soon as in the foetus the articulation of the brain has been completed,
the first Mover turns to it, rejoicing over the greatness of Nature’s art, and breathes into it a new spirit, replete with power,
that . . . becomes one single soul, that lives and feels and turns itself back to itself.

My Catholic, pro-life students peppered me with questions: “Does Dante not believe that the embryo is initially a person? Would Dante have supported abortion?” The most pressing question, was, perhaps: “If Dante had the scientific information we have now, would he still think the fetus was more plant-like before it became a human?”

This last question gets at how Dante—and the ancients—treat science. Dante’s understanding of embryology was based on the most up-to-date medical information of his day, but it was only up-to-date in the most limited sense. It was based upon the views of the fetus espoused by the fifth- or fourth-century b.c. Hippocratic corpus and Aristotle’s fourth-century b.c. On the Generation of Animals.

The debate over when life begins is not a modern phenomenon, but one the ancients understood and considered crucial. Before there were pro-life and pro-choice blogs and op-eds, there were treatises on the embryo, and they were written in Greek.

The people who began this debate were not Christian; they were Hellenic philosophers who also considered themselves what we moderns would term “scientists.” While many did not lay claim to an absolute protection for the human embryo from the beginning, they did, as philosophers and scientists both, ruminate on the beginnings of embryonic ensoulment: whether the embryo could be said to be bereft of a soul until the moment of its first breath (which is to say, at birth), or whether it attained a soul gradually during its development in utero, or whether it had a soul at the moment of conception.

The ancients based their opinions on data gathered from studies of the pregnant mother or through the dissection and vivisection of pregnant animals. While the arguments on the nature of the embryo were complicated and far-ranging, differing from author to author, their ideas of whether an embryo had a soul were based on the limited evidence available. Likely their opinions would have been quite different with the knowledge modern technology affords us.

The “at first breath” argument is offered most comprehensively in To Gaurus: On How Embryos are Ensouled, a text believed to have been written by Porphyry, a third-century student of the “founder” of Neoplatonism, Plotinus. He argues that the fetus, rooted and plant-like, does not receive a soul and hence is not a human person until its first breath.

In the introduction, Porphyry suggests that those speculating on the nature of the embryo can be divided into four camps according to their views on the moment of ensoulment: with the creation and release of semen; when the embryo is first formed (between the first thirty and forty-two days of pregnancy); when the embryo first moves (between the first three and four months of pregnancy); and, finally, at birth.

The first group he treats believes the embryo is ensouled when the semen is released into the womb. While the prevailing view on ancient embryology held that the fetus was ensouled at some point during development, many Stoic philosophers interpreted Plato’s Timaeus and Laws as describing the ensoulment of the embryo at the time of conception.

Christian theologians held a version of this position. Some, like Tertullian in his Apologia, argued that it is unlawful to destroy the soul even while it is coming into birth, for “he is a man who is to be a man,” because “the fruit is always present in the seed.” Basil of Caesarea, in his letters to Amphilochius, charges the woman who engages in abortion with murder and states that it is not permissible for men to make any distinction between whether a person is formed or unformed.

The second and third groups Porphyry delineates can be collected into one: those who believe the embryo attains a soul at some point during its development. Those adhering to the gradual process of ensoulment include Aristotle, who in his On the Generation of Animals attributes to the earliest embryo a vegetative existence animated or informed by a nutritive soul; to the later embryo, resembling a little animal, a “sensitive soul”; and to the formed fetus, recognizably human, a rational or intellectual soul that encapsulates but does not replace the other two.

The Hippocratic Nature of the Child likewise held a gradualist view of the development of the fetus. As the time for birth drew near, the fetus moved from the animal-like embryo to the human child.

In his Formation of the Fetus, Galen says that the fetus gradually moves from a plant-like state until in the final period it acquires the capacity for the heat of a warm-blooded creature, its heart begins to beat, and it moves on its own. Although a gradualist in his determinations on fetal development, he criticizes the Hippocratic opinion, which denied that the fetus moves on its own and attributed the apparent motion to a swaying of the uterus. He insists that the fetus moves by impulse—an important attribute of the animal, as opposed to the plant.

In To Gaurus, Porphyry’s main concern is to establish the plant-like nature of the embryo over and above its animal-like qualities. To do so, he defines the psychological features of animals as including sensation, impulse, and movement, qualities he denies a growing fetus possesses. He argues that just as plants nourish themselves through their roots, so the fetus nourishes itself through its “stalk-like” umbilical cord, while the newborn baby eats through its mouth like an animal.

He further denies the animal soul to the developing fetus, describing how both plants and fetuses experience passive motion, while animals and newborn babies move themselves. He also argues that the fetus lacks sensation, as is apparent in its lack of self-motion and silence.

Porphyry reserves the moment of ensoulment for the time of birth. At the moment of birth, the self-moving individual soul arrives into the body of the newborn in an ensouling process controlled by a metaphysical entity called “the World Soul.”

In all these descriptions, we see two motivations at work: a scientific one and an ideological one. What the ancient debates on the question of the embryo have in common is a scientific adherence to what is empirically known about the embryo. But other concerns affected their scientific determinations.

Platonist metaphysics drives many of Porphyry’s views in To Gaurus. He must maintain the structure of the Neoplatonic cosmos in his understanding of when a body receives a soul. In order for the World Soul to have power over the individual soul, the body can only receive a soul at the time of birth. This should lead the reader to question his science (already questionable given the limitations of medical observation in the fourth century a.d.).

Ultimately, however, the ancient philosophers contemplating embryology thought of themselves as scientists. That the science—and presumably changes in it—could so explicitly shape their philosophical conclusions is the primary difference between the ancient debates on embryology and the modern one. In our world, the question driving the debate is not how an embryo develops but whether the liberty of one life (the mother) trumps the existence of another. Hence, in the modern debates, we see figures like Peter Singer tying themselves up in philosophical knots to show that even a school-aged child should not be considered a rational person.

In the ancient debates, scientists and philosophers used criteria such as reaction to stimuli, modes of nutrition, and origin of motion to determine when the embryo receives a soul and can be considered a person. Knowing what we know today, Hippocrates, Galen, Porphyry, and Aristotle would be required to admit that the fetus reacts to stimuli, such as light and sound, and is self-moving—traits far from “plant-like.”

For all of their idiosyncratic talk of plant and animal souls, the ancients at least would have recognized a twelve-week-old baby moving in his mother’s womb as a person with a soul. In the journey to protect the unborn, O Statius, we still have a long way to go before we reach Paradise.

Sarah Klitenic Wear is associate professor of classics at Franciscan University of Steubenville.