Aristotle's early works consisted largely of dialogues, many of which were lost. His model for these dialogues was, of course, Plato. At the height of Plato's productivity, Plato sought not to establish doctrines but rather to depict the philosopher in the dramatic process of discovery. Moreover, the process was not merely intellectual, for it took place in the context of politics, society, and personal struggle, over which philosophy had to emerge. Later in Plato's career, however, which is when Aristotle came to the Academy, Plato departed from this formula and placed less emphasis on aesthetic composition. His dialogues ceased to depict genuine intellectual struggle and instead consisted largely of prolonged exposition with occasional interjections of agreement. At least part of the reason for this change was that Plato's interests turned to more abstract studies, and he felt that more direct exposition would convey his ideas in a clearer manner.

Nevertheless, all members of the Academy wrote dialogues because they were the method established by Plato. Even Aristotle did not yet recognize that the method perfected by Plato might not be capable of imitation. His own dialogues, however, did take a different approach that went more along the lines of Plato's later works. Abandoning the question-and-answer dialogue, epitomized by the figure of Socrates, Aristotle employed longer opposing speeches. Some literary historians have thus argued that Aristotle induced the decline of the dialogue form, but it is more accurate perhaps to say that he simply adapted an old form to the changing direction of philosophy. His dialogues, moreover, were a closer imitation of real conversations and debates taking place in the Academy, and imitation was the point of the original dialogues.

Of his surviving early works, several deserve individual attention. The dialogue Eudemus was written shortly after the title character, a real-life friend of Aristotle's, died in 354–353 B.C. Eudemus had been banished from Cyprus and fallen ill in Thessaly, and his doctors had essentially given up. In a dream, a handsome young man appeared to deliver three prophecies: Eudemus would soon recover, the tyrant of Pherae would fall, and after five years Eudemus would return to his home. The first two events took place as prophesied, and five years later Eudemus fell in battle, returning to a figurative home. Aristotle used this story as a starting point to discuss the soul–in particular its immortality–and dealing largely with issues brought up in Plato's Phaedo. One long passage of Phaedo refutes the idea that the soul is simply a state of harmony within the body. But while Plato dealt with the issue somewhat cumbersomely, Aristotle attempted to simplify the argument. One of his arguments went as follows: harmony has an opposite, namely disharmony. But since the soul has no contrary, it cannot be a state of harmony.

In his Protrepticus, Aristotle continued to illuminate Platonic ideas, using Eudemus as a model, but from his own unique perspective. His central argument is that intellectual wisdom is the chief virtue and the only real basis of happiness. Through various metaphors and illustrations, he attempts to prove that a life without philosophy is inevitably barren.

In a later work, entitled simply Philosophy, Aristotle began to show more significant differences from Plato. The work consisted of three self-contained books. In the first Aristotle attempts a history of philosophy, in conjunction with religion, tracing the two areas as parts of a single point of development. While the first book gives Plato an illustrious spot in the context of history, the second book consists of a cogent refutation of Plato's Theory of Forms. By the third book, Aristotle has established the foundational viewpoint from which to offer his own views. Although he argues confidently for the existence of God, his actual conception is unclear: sometimes he speaks of God as the universe, other times he speaks of God as pure intellect. Nevertheless, Philosophy is one of Aristotle's first truly original works in which he clearly rejects Platonic ideas and presents several of his own.

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