What Orpheus delivered in hidden allegories, Pythagoras learned when he was initiated into the Orphic Mysteries, in which Plato next received a perfect knowledge from the Orphic and Pythagorean writings.
In this connexion it was pointed out by H. P. Blavatsky, the foundress of the Theosophical Society (Isis Unveiled, vol. II, p. 39, Point Loma edition) that Plato himself in his Letters declares that his teachings were derived from ancient and sacred doctrines. In the Seventh Letter of the collection which has come down to us he says:
It is ever necessary to believe in the truth of the Sacred Accounts of the Olden Time, which inform us that the soul is immortal and has judges of its conduct and suffers the greatest punishments when it is liberated from the body. Hence it is requisite to regard it a lesser evil to suffer than to commit the greatest sins and injuries.
It is unjustifiable to assume as scholars usually do that we are in a position to judge correctly of all of Plato's thoughts because, most fortunately, it appears that all of his published works have been preserved. The last thirty-eight years of Plato's life were spent as Scholarch or Head of the Platonic School among the olive groves of the Academy where the philosopher dwelt with some of his principal students, namely, his successor and pupil Speusippos, Xenokrates, and others, teaching Divine Wisdom freely to those who were able to understand. The fact that Aristotle refers to various teachings of Plato not now extant in the Platonic works, as well as the request in the Second of our Platonic Letters that the letter be burned after its frequent reading so that it may not fall into improper hands, both afford corroborative evidence of the tradition that Plato refused to publish any of his numerous lectures and oral teachings. It is therefore a priori probable that Plato treated philosophy in two distinct ways, one treatment intended for public circulation and the other intended for School instruction. If this be true, presumably his published dialogs give mere indirect hints, illustrations, and applications of the central principles of his teachings, which were revealed only orally to a selected audience. Doubtless the character of his oral instructions also varied and certain teachings were given only to a few of his more advanced students, as even Grote admits. Therefore in seeking to understand Plato it is important to recollect that today "the Prince of Western Philosophers" is known only from his Dialogs, while his teachings as Scholarch are now unknown. It is, however, certain from the statement of Aristotle in regard to Plato's lectures "On the Supreme Good," that Plato in his oral instructions taught Pythagorean Doctrines, and dealt with the highest and most transcendental concepts in a mystical and enigmatical way.
In regard to this there are important declarations in the extant Letters of Plato, Letters which it is orthodox to declare to be apocryphal, but whose genuineness is rightly defended by Grote in his Plato and Other Companions of Socrates. In the Second Letter, which is addressed to Dionysios the Younger of Syracuse, Plato uses some very suggestive language in referring to the effect upon the newly fledged student of entering the School:
I must speak to you in enigmas that should this tablet meet with any accident by land or by sea, he, who might perchance read it, may not understand. This has not happened to you alone but in truth no one when he first hears me is otherwise affected. Some have greater troubles, others less but nearly every student has a struggle of no slight power from which in truth he is freed only with difficulty. Be careful, however, that these discussions do not become known by men devoid of knowledge—discussions which if continually heard for many years at length with great labor are purified like gold. Many persons apt at learning and remembering have heard them for not less than thirty years and after testing them in every way have recently declared that those things which formerly appeared to them to be least worthy of belief now appear to be most worthy of belief and perfectly clear. The most important protection is to learn but not to commit to writing because what is written will almost certainly become public knowledge. Therefore on this account I have never myself at any time written anything on these subjects. There neither is nor ever shall be any treatise of Plato. The opinions called by the name of Plato are those of Socrates in his days of youthful vigor and glory.
These words of Plato, if admitted to be genuine, especially when linked with the following statements made in the Seventh of our Letters, show the futility of the current dogmatism of what purport to be correct and complete modern expositions and criticisms of Platonism, and ought to instil more humility in the orthodox dogmatists who strive to interpret the thoughts of the Master. The declarations referred to in the Seventh Letter are set forth as follows:
In regard to all who either have written or who shall write confidently stating that they know about what I am occupied, whether they claim to have heard it from me or from others or to have discovered it themselves, I can say that it is impossible for them to know anything as to my beliefs about these matters; for there is not and never will be any composition of mine about them. For a matter of this kind can not be expressed in words as other sciences are. But by a long acquaintance with the subject and by living with it suddenly a light is kindled in the mind, as from a fire bursting forth, which being engendered in the soul feeds itself upon itself.
He adds: