 It is clear, at any rate, that in Book X Aristotle gives a fuller account of what pleasure is than he had in Book VII. We should take note of a further difference between these two discussions: In Book X, he makes the point that pleasure is a good but not the good. He cites and endorses an argument given by Plato in the Philebus: If we imagine a life filled with pleasure and then mentally add wisdom to it, the result is made more desirable. But the good is something that cannot be improved upon in this way. Therefore pleasure is not the good (1172b23–35). By contrast, in Book VII Aristotle strongly implies that the pleasure of contemplation is the good, because in one way or another all living beings aim at this sort of pleasure. Aristotle observes in Book X that what all things aim at is good (1172b35–1173a1); significantly, he falls short of endorsing the argument that since all aim at pleasure, it must be the good.