  In 2008, Romana Martorelli Vico published the first critical edition of Giles’ De formatione corporis humani in utero. With this work, completed between 1285 and 1295, Giles took a stance in the much debated question of the respective roles of male and female parents in conception. The Galenist view, going back to Hippocrates, was that both male and female contributed sperm, so that the offspring could have characteristics from both parents. On the contrary, Aristotle had held that only the male alone contributed sperm containing an active and formal principle to conception, while the female provided only the matter of the fetus. Giles was well acquainted with these different positions and with the efforts to reconcile the diverging approaches of medici and philosophi, which could be traced back to Avicenna. Leaning on Averroes’ Colliget, however, Giles rejected any attempt to attribute a formal role to the female sperm, even if it is conceived as subordinate to the male one. On the contrary he maintained that it can contribute only in a passive way to conception, while what was called “female sperm”, i.e., the vaginal secretion, has a subservient, helpful but by no means necessary function. It helps the male sperm to inseminate female matter, but does not add anything essential to the new being. In this way, Giles intended to stress the superiority of the philosophical, theoretical approach to such problems with respect to the traditions of medical learning, even when the latter seemed to be supported by empirical evidence (Hewson 1975; Martorelli Vico 1988). Empirical evidence such as the resemblance of the offspring to the mother was e.g., explained away as an example of stronger resistance of female matter to the action of form (Martorelli Vico 2002). After conception the human embryo begins a development which goes through different stages. Comparing these stages to the embryos of various animals Giles, like Thomas Aquinas, supported an interpretation of the fetal development which would be exploited many centuries later by the so-called “recapitulation theory” (Hewson 1975, 99). Giles maintained, however, that “the organic fetal body is not to be called a pig, a bear, or a monkey, but something immediately disposed to becoming man” (Hewson 1975, 100). This position apparently implies that human life does not fully begin at the moment of conception. Although such a thesis can be brought to bear on the moral judgment concerning abortion, Giles does not seem interested in tackling from this point of view an issue which would become central for what nowadays is called bioethics.