Aristotle is often considered the most level headed of the ancient philosophers and rightly so. While there is strong evidence that Plato is alluding to certain of Orphic or Pythagorean mysticism in dialogues such as the Phaedrus and Symposium, there is generally little reason to believe that the Macedonian philosopher was a hidden occultist.
However, there is a passage at the beginning of Plutarch’s Life of Alexander that always strikes me as odd:
It would appear, moreover, that Alexander not only received from his master his ethical and political doctrines, but also participated in those secret and more profound teachings which philosophers designate by the special terms “acroamatic” and “epoptic,”and do not impart to many. For after he had already crossed into Asia, and when he learned that certain treatises on these recondite matters had been published in books by Aristotle, he wrote him a letter on behalf of philosophy, and put it in plain language. And this is a copy of the letter. “Alexander, to Aristotle, greeting. Thou hast not done well to publish thy acroamatic doctrines; for in what shall I surpass other men if those doctrines wherein I have been trained are to be all men’s common property? But I had rather excel in my acquaintance with the best things than in my power. Farewell.” Accordingly, in defending himself, Aristotle encourages this ambition of Alexander by saying that the doctrines of which he spoke were both published and not published; for in truth his treatise on metaphysics is of no use for those who would either teach or learn the science, but is written as a memorandum for those already trained therein.
A couple of things to consider.
Aristotle and Alexander studied together at the precinct of the nymphs near Mieza.
Alexander learned medicine from Aristotle, which was often associated with natural magic.
While there is no known connection between Alexander’s mother Olympias and Aristotle, as far as I know, Olympias was a devotee of the Orphic cult and practiced some sort of serpent worship. This is not to say that Aristotle has necessarily had hidden Orphic teaching in his work.
But we are left with few interesting questions.
Did Alexander pick up Orphism from his mother?
Did Alexander and Aristotle worship together or practice and early form of theurgy at Mieza?
What is the hidden teaching of the Metaphysics?