It's interesting to read Plutarch's Life of Alexander on the education of Alexander:
After this, considering him to be of a temper easy to be led to his duty by reason, but by no means to be compelled, he always endeavoured to persuade rather than to command or force him to anything; and now looking upon the instruction and tuition of his youth to be of greater difficulty and importance than to be wholly trusted to the ordinary masters in music and poetry, and the common school subjects, and to require, as Sophocles says--"The bridle and the rudder too," he sent for Aristotle, the most learned and most celebrated philosopher of his time, and rewarded him with a munificence proportionable to and becoming the care he took to instruct his son. For he repeopled his native city Stagira, which he had caused to be demolished a little before, and restored all the citizens, who were in exile or slavery, to their habitations.
In the potted biographies we often use, very little thought seems to be taken to Aristotle's motivation for becoming the tutor of Alexander. But the story as told by Plutarch seems very strongly to imply that Aristotle did it to save his hometown and its people.
Plutarch also attributes an esoteric as well as exoteric component to Aristotle's curriculum:
As a place for the pursuit of their studies and exercise, he assigned the temple of the Nymphs, near Mieza, where, to this very day, they show you Aristotle's stone seats, and the shady walks which he was wont to frequent. It would appear that Alexander received from him not only his doctrines of Morals and of Politics, but also something of those more abstruse and profound theories which these philosophers, by the very names they gave them, professed to reserve for oral communication to the initiated, and did not allow many to become acquainted with. For when he was in Asia, and heard Aristotle had published some treatises of that kind, he wrote to him, using very plain language to him in behalf of philosophy, the following letter. "Alexander to Aristotle, greeting. You have not done well to publish your books of oral doctrine; for what is there now that we excel others in, if those things which we have been particularly instructed in be laid open to all? For my part, I assure you, I had rather excel others in the knowledge of what is excellent, than in the extent of my power and dominion. Farewell." And Aristotle, soothing this passion for pre-eminence, speaks, in his excuse for himself, of these doctrines as in fact both published and not published: as indeed, to say the truth, his books on metaphysics are written in a style which makes them useless for ordinary teaching, and instructive only, in the way of memoranda, for those who have been already conversant in that sort of learning.
The comment that the Metaphysics is "useless for ordinary teaching" is amusing, but the comment about the memoranda pretty clearly gives a Platonic interpretation to the book, since this is one of the purposes of teaching and of writing in particular that Plato indicates in his own accounts of education. Plutarch's characterization of the exoteric education, although presented as partly more speculative, would also be more recognizable to philosophers today:
Doubtless also it was to Aristotle that he owed the inclination he had, not to the theory only, but likewise to the practice of the art of medicine. For when any of his friends were sick, he would often prescribe them their course of diet, and medicines proper to their disease, as we may find in his epistles. He was naturally a great lover of all kinds of learning and reading; and Onesicritus informs us that he constantly laid Homer's Iliads, according to the copy corrected by Aristotle, called the casket copy, with his dagger under his pillow, declaring that he esteemed it a perfect portable treasure of all military virtue and knowledge.
Plutarch also suggests that they had some kind of falling out, although he's so vague it's unclear what it would be; Plutarch himself is more interested in noting that, despite the falling out, Alexander retained the passion for learning and reading that he had received from Aristotle.
