Aristippus asked Socrates whether he knew anything good, so that if he answered by naming food or drink or money or health or strength or valour or anything of that sort, he might at once show that it was sometimes an evil.
Socrates, however, knew very well that if anything troubles us what we demand is its cure, and he replied in the most pertinent fashion. ‘Are you asking me,’ he said, ‘if I know anything good for a fever?’
‘Oh, no,’ said the other.
‘Or for sore eyes?’
‘Not that, either.’
‘Or for hunger?’
‘No, not for hunger.’
‘Well, then,’ said he, ‘if you ask me whether I know a good that is good for nothing, I neither know it nor want to know it’
Xenophon - Memorabilia.