The analogy between young men and sick people is that

  Young men have strong passions and tend to gratify them indiscriminately. Of the bodily desires, it is the sexual by which they are most swayed and in which they show the absence of self-control. They are changeable and fickle in their desires, which are violent while they last but quickly over; their impulses are keen but not deep-rooted and are like sick people’s attacks of hunger and thirst. They are hot-tempered and quick-tempered and apt to give way to their anger; bad temper often gets the better of them, for owing to their love of honour they cannot bear being slighted, and are indignant if they imagine themselves unfairly treated. While they love honour, they love victory still more, for youth is eager for superiority over others, and victory is one form of this. They love both more than they love money which indeed they love very little not having yet learnt what it means to be without it. They look at the good side rather than the bad, not having yet witnessed many instances of wickedness. They trust others readily because they have not yet been cheated. They are sanguine; nature warms their blood as though with excess of wine and besides that, they have as yet met with few disappointments. Their lives are mainly spent not in memory but in expectation for youth has a long future before it and a short past behind it: on the first day of one’s life, one has nothing at all to remember and can only look forward. They are easily cheated owing to the sanguine disposition just mentioned. Their hot tempers and hopeful dispositions make them more courageous than older men are; the hot temper prevents fear and the hopeful disposition creates confidence. We cannot feel fear so long as we are feeling angry, and any expectation of good makes us confident.