PROOEMIUM.

of the knower. Therefore, the more a man knows of God, the more he is assimilated to Him. The text says that among all motions, generation is the nobler, taking it as the education of the soul or the formation of the fetus in the womb; how this is a motion, it will be seen. For which note that motion is twofold. One is a motion that casts something away from a substance, just as the heating of water casts away coldness, and it moves from white to black. The other is a motion that does not cast any perfection away from the substance of the motion, such as the motion of the heavens, which does not cause anything to be corrupted from the substance of the heavens. Now, generation is a motion casting something away from the substance of the thing, because the menstrual flow that moves toward the formation of man is transmuted. Hence Averroes says in the first book of the Physics: In the generation of man, a part of the semen does not cease to be corrupted, and a part of the man is generated, until the whole form is completed.

ON THE GENERATION

Of the Embryo.

CHAPTER I.

After our discourse has been prefaced concerning those things that incline the intention of the listener to the subject matter of the style, it is appropriate to descend to the matter of the work, and first to see about the generation of the embryo. According to which it is to be noted diligently and committed to memory, that every man who is generated naturally is generated from the semen of the father and the menstrual flow of the mother, according to