Aristotle, Nicomachean Ethics
H. Rackham, Ed.

[4] Again, they postulate¹ that the Good is perfect, whereas a motion or process of generation is imperfect, and then they attempt to prove that pleasure is a motion or process. This appears to be a mistake. （a） It would seem that pleasure is not a motion; for we hold it to be a property of all motion to be quick or slow—if （as with the motion² of the firmament） not absolutely, then relatively to some other moving body. But pleasure possesses neither absolute nor relative velocity. You can become pleased quickly, just as you can get angry quickly: but you cannot be pleased quickly, nor yet more quickly than somebody else, as you can walk, grow, etc., more quickly than somebody else. It is possible to pass into a pleasurable state quickly or slowly, but not to function in that state—i.e. to feel pleasure—quickly.