Thus every vicious tendency contracted by the soul during its abode in this world has for this soul consequences which their long duration makes more momentous. If virtue enables it to rise upward at each new birth and to acquire, as the ages revolve, an ever increasing perfection, perversion of character produces effects which are calamitous not only in this life but also in several other lives through the centuries. Moral laws are no less infallible than physical laws. Right or wrong, every act has to be paid for with harm or benefit in the long chain of incarnations. By his acquired disposition, man determines his future throughout a sequence of generations; the evil he suffers is to be imputed not to the creator but to himself. A bust of Plato found at Tivoli and now preserved in San Francisco[451] has graven on it the following sentence of the Master as to the lot of immortal souls: “The fault is the chooser’s; God is without fault”—Αἰτία ἑλομένω, ὁ θεὸς ἀναίτιος. The very fact of birth was a pain for the soul, since it tore it from its celestial home and plunged it into a soiled and troubled world; consequently it was not necessary for the soul’s chastisement that it should descend into the body of animals. Indeed, certain thinkers rejected this kind of metempsychosis: a reasonable spirit could not, they held, dwell in a being deprived of reason. Transmigration occurred therefore exclusively from man to man and from beast to beast. Such was the opinion defended by Porphyry and Jamblichus, who, in order to dispose of the texts of Plato which were contrary to this theory, upheld that he spoke figuratively, and that his “asses,” his “wolves” and his “lions” signified persons who resembled these beasts in ignorance or ferocity.[452] It is seen that this metempsychosis was getting far away from that which had its origin in the primitive beliefs. The “cycle of generation” was no longer conceived as a flux of life circulating throughout the variety of the animate beings peopling the earth, but as the descent and the ascent of a psychic essence, passing alternately from heaven to earth and from earth to heaven. It is to these doctrines that Virgil alludes when in the Aeneid he shows us, gathered in a remote place of the Elysian Fields, the shades whom after a thousand years a god calls to come in a great troop to the river Lethe, there to drink the forgetfulness of the past, whereby “they begin again to wish to return to the body.”[453] * * * * *