But after they have been in college a term, and have been knocked about and handled in a rough but good-humored manner by youths of their own age, they realize that it would be the most foolish thing in the world to betray resentment.

If one shows that he is hurt, he knows that he will be called the class booby, and teased unmercifully, so he is simply forced to drop his foolish sensitiveness.
Thousands of people are out of positions, and cannot keep places when they get them, because of this weakness.

Many a good business man has been kept back, or even ruined, by his quickness to take offense, or to resent a fancied slight.

There is many a clergyman, well educated and able, who is so sensitive that he can not keep a pastorate long.

From his distorted viewpoint some brother or sister in the church is always hurting him, saying and thinking unkind things, or throwing out hints and suggestions calculated to injure him in the eyes of the congregation.
Many schoolteachers are great sufferers from over-sensitiveness.
Remarks of parents, or school committees, or little bits of gossip which are reported to them make them feel as if people were sticking pins in them, metaphorically speaking, all the time.