From Herbert Chapman on Football, a posthumous collection of his Sunday Express articles that was published as a memorial to him in 1934:
What do we mean by temperament? An old Scottish golfer described it as simply common sense, and he was probably correct. But perhaps the term self-control is more expressive and better understood. I often think of the footballer as going out into the middle before a big crowd on an important occasion in much the same way as a man who has to make a speech. The one knows what he hopes to do, and the other what he intends to say, but in each case there is a very real danger of his getting hot and bothered and thrown off his balance. The trouble in regard to both of them is a mental or nervous one, and in the excitement the lose their self-control.
A footballer may be affected by the most trivial incident. He may make a mess of his first pass or shot, he may miss a tackle. Fear seizes him, and he becomes over-anxious. You see a man take the ball down brilliantly, but as soon as he reaches the penalty area, and it is time to make the final effort, he does something foolish. It is, in fact, not unusual for men in these circumstances even to shut their eyes. One moment they are complete masters of themselves, and the next all their self-control has gone. It is all very strange and difficult to understand.