Aristotle feels this so strongly with reference to Plato's external, as contrasted with his own immanent, teleology that, forgetting his own concession elsewhere, he once roundly asserts that the final cause is 'not touched by the Ideas'. Again, what is the relation of the Idea of the Good to other ends (Ideas) or to the special functions of things? Efficient causes Plato attributes at one time to Idea, at another to soul: which is his real doctrine? and what is the relation of Idea to soul? Aristotle, therefore, while willing to admit that Plato made 'stammering' efforts in the direction of efficient and final causes, was perfectly justified in thinking that he had not 'fully worked them out'.
Plato