Experience.

The natural disposition of most people is to clothe a commander of a large army whom they do not know, with almost superhuman abilities. A large part of the National army, for instance, and most of the press of the country, clothed General Lee with just such qualities, but I had known him personally, and knew that he was mortal; and it was just as well that I felt this.

My experience has taught me two lessons: first, that things are seen plainer after the events have occurred; second, that the most confident critics are generally those who know the least about the matter criticized.

Ulysses S. Grant