The doctrine of Plato was epoch-making in the history of human genius, but it was not his own invention, for, realising that there is no truth apart from religion, he went to consult the priests of Memphis and to obtain initiation into their Mysteries. He is even credited with a knowledge of the Jewish sacred books.[88] In Egypt, however, his initiation could have been imperfect only, for the priests by that time had forgotten themselves the import of their primeval hieroglyphics, as is indicated by the history of that priest who spent three days in deciphering a hieratic inscription found in the tomb of Alcmene and sent by Agesilaus, King of Sparta. Cornuphis, who was doubtless the most learned among the hierophants, consulted the old collections of signs and characters; in the end he found that the inscription was in the script of _proteus_, being the Grecian name of the _Book of Thoth_, consisting of movable hieroglyphics, capable of variations as numerous as there are possible combinations of characters, numbers and elementary figures. But the _Book of Thoth_, being the key of oracles and the elementary work on science, should not have involved such long research before its signs were identified, if Cornuphis had been really proficient in the Sacerdotal Art. Another proof that primeval truths were obscured at this period is the fact that the oracles which registered their protest on the subject were in a style that was understood no longer. After his return from Egypt, Plato was journeying with Simmias on the confines of Caria when he was met by some men of Delos, who begged him to interpret an oracle of Apollo. It declared that to make an end of the woes in Greece the cubic stone must be doubled. The attempt had been made with a stone kept in the temple of Apollo; but the work of doubling it on every side resulted in a polyhedron having twenty-five surfaces; to restore the cubic form they had to increase it twenty-six times the original volume of the stone, by a process of successive doubling. Plato sent back the emissaries to the mathematician Eudoxus,[89] saying that the oracle had counselled the study of geometry. Whether he did not himself understand the deep sense of the symbol or disdained to unveil it to the ignorant are points which must be left to conjecture; but that which is certain is that the cubic stone and its multiplication explains all secrets of sacred numbers, including the mystery of perpetual motion, hidden by adepts and pursued by fools under the name of squaring the circle.[90] By this cubic agglomeration of twenty-six cubes about a single central cube, the oracle indicated to the Delians not only the elements of geometry but the key of creative harmonies, explained by the inter-relation of forms and numbers. The plan of all great allegorical temples throughout antiquity is found in the multiplication (_a_) of the cube by the cross, (_b_) about which a circle is described, and then (_c_)