Book 2
3
I would then ask Erasistratus himself to inform me what the altering, coagulating, and shaping agent is. He would doubtless say, Either Nature or the semen, meaning the same thing in both cases, but explaining it by different devices. For that which was previously semen, when it begins to procreate and to shape the animal, becomes, so to say, a special nature.The spermatozoon now becomes an organism proper. For in the same way that Phidias possessed the faculties of his art even before touching his material, and then activated these in connection with this material (for every faculty remains inoperative in the absence of its proper material), so it is with the semen: its faculties it possessed from the beginning,Galen attributed to the sperma or semen what we should to the fertilized ovum: to him the maternal contribution is purely passive — mere food for the sperm. The epoch-making Ovum Theory was not developed till the seventeenth century. cf. p. 19, note 3. while its activities it does not receive from its material, but it manifests them in connection therewith.
