ALBERT. MAGN. LIB.

the intention of all philosophers and physicians. And I say physicians, because Aristotle did not posit that the father's semen yields to the substance of the fetus, but he says the fetus proceeds only from the menstrual flow, and afterward he posits that it exhales vaporably. Physicians, however, say that the whole semen, both on the part of the father (which is called sperm) and the mother (which is called the menstrual flow), yields to the substance of the fetus.

Chapter of the first executive part, in which he wishes to address the matter, namely to show the generation of the embryo or fetus. There is no controversy between physicians and philosophers. For philosophers say that the man's semen, joined to the female menstrual flow, acts upon the woman's menstrual flow as an artisan acts upon the work. Whence, just as the carpenter is only the efficient cause and the house is the effect, in such a way that he alters and disposes the matter of the house, so also the man's sperm alters the woman's menstrual flow to the form of a man. And they posit this because it seems that when the father is corrupted, the generation of man occurs, and the transmutation of the woman's semen occurs; therefore, it is to posit an efficient cause by which, when the father is corrupted, the woman's menstrual flow is transmuted. And because the end and the effect do not coincide, therefore the man's sperm does not enter the matter. But physicians say the opposite, namely that man is made from the noblest matter; therefore, for the semen to enter under the matter of the female fetus is a superfluity of the second digestion, but the man's sperm is better cooked and digested, therefore it