few grams altogether, in the human cortex: from this may be seen how minute and subtly delicate they are. We should not fail to appreciate this fear of their easy liability to fatigue, for it is a very real educational matter. At the same time the brain may be trained so we need not coddle it. Most people undoubtedly do coddle their brains, but usually from human laziness, not because deeply wise in hygiene!
Habituation to the thinking process. Habit makes thinking much easier than it is at first. Habituation makes thought a continuous subconscious process. Just as we know that worry is worse for the health than an occasional fright; and just as a steady drinker suffers more pathologic harm than the man who goes off on an occasional drunken spree; so, on the other hand, the continuous use of thought most impresses the brain. The habit of learning-interest must be acquired; but this mental attitude soon becomes more or less permanent. Habituations of all kinds, of course, are more or less accumulative. It is "the first step that counts" we have often heard, and all habit grows with what it feeds upon. Thought is a habit, subconscious like all of them. In order to acquire the thinking-
