History consists of the general and the particular. The existence of the general is the reason why history repeats itself. In the annals of the past it is surprising to find, time and again, that what is often considered as modern and unique has happened before. Closer study reveals that men, when confronted with a similar set of circumstances have reacted, throughout recorded history, in patterns revealing a marked degree of similarity. If we are to gain a measure of rational control over an otherwise frequently anti-rational—and therefore anti-human—world, it is essential that we know these patterns. They show that men so often do what they do not want to do; they are caught in a chain of circumstances which they could have broken only if they had realized what the last link would be while they were forging the first or were permitting events to forge it for them.