As to this puzzling question there arose in the Alexandrian period a theory unknown to ancient Greece,—we have already touched on this point[420]—the theory that man is formed not of two elements but of three, namely, the soul (ψυχή, _anima_), the shade (σκιά, εἴδωλον, _umbra_, _simulacrum_) and the body (σῶμα, _corpus_). This doctrine claimed to be justified by a passage in Homer, in fact an interpolation, as to the apotheosis of Hercules, but it was manifestly borrowed from Egyptian religion by the Pythagoreans of Alexandria. For Egyptian religion is “polypsychic” and distinguishes different kinds of souls. So the _ka_ or “Double” has been explained as a living and coloured projection of the individual whom it reproduced feature by feature, which inhabited the tomb, but could leave it and return to it as freely as a man to his house. The _baï_, on the other hand, is thought to be a more refined matter which enclosed a portion of the celestial fire and which departed to another world. Certain Alexandrian Pythagoreans therefore admitted that when the soul was not entirely purified, it remained joined to its idolon in the infernal regions, which were for them situated in the atmosphere, but they held that when it had entirely freed itself from matter it rose towards the ether, and left only the _idolon_ in the neighbourhood of the earth.[421] This theory was to be variously transformed, but it is at the foundation of all the subsequent development of the doctrines as to the return of the soul to heaven. The triple division most usually adopted is not the one I have just cited but the division into reason (νοῦς or πνεῦμα), soul (ψυχή) and body. What becomes in this case of the image (εἴδωλον)? The theologians assimilated it to the irrational soul or ψυχή, as opposed to the higher understanding. This image thus became the seat not only of vegetative and unconscious life—a theory which would be in conformity with the Homeric sense of the word—but also of sensitive and emotional life. This soul or shade at first remained united to the _nous_, which it surrounded with its vaporous envelope. Even after it had left the earthly body, reason was still imprisoned in an aerial body: the two dwelt in the infernal regions, that is, in sublunary space, until they had been purified by the elements. They then, as we have seen elsewhere,[422] left the atmospheric Hades in order to be admitted into the Elysian Fields, that is to say, into the moon. There the thin veils in which reason was still wrapped were dissolved. Reason, a sublime essence, rose again towards the sun and the higher spheres.