If, then, the brain-user wishes to be healthy, he must limit his hours of work according to rules which will come of experience, and which no man can lay down for him.  Above all, let him eat regularly and not at too long intervals.  I well remember the amazement of a distinguished naturalist when told that his sleeplessness and irregular pulse were due to his fasting from nine until six.  A biscuit and a glass of porter, at one o’clock, effected a ready and pleasant cure.  As to exercise in the fresh air, I need say little, except that if the exercise can be made to have a distinct object, not in the way of business, so much the better.  Nor should I need to add that we may relieve the thinking and worrying mechanisms by light reading and other amusements, or enforce the lesson that no hard work should be attempted during digestion.  The wise doctor may haply smile at the commonplace of such directions, but woe be to the man who neglects them!

When an overworked and worried victim has sufficiently sinned against these simple laws, if he does not luckily suffer from disturbances of heart or stomach, he begins to have certain signs of nervous exhaustion.

As a rule, one of two symptoms appears first, though sometimes both come together.  Work gets to be a little less facile; this astonishes the subject, especially if he has been under high pressure and doing his tasks with that ease which comes of excitement.  With this, or a little later, he discovers that he sleeps badly, and that the thoughts of the day infest his dreams, or so possess him as to make slumber difficult.  Unrefreshed, he rises and plunges anew into the labor for which he is no longer competent.  Let him stop here; he has had his warning.  Day after day the work grows more trying, but the varied stimulants to exertion come into play, the mind, aroused, forgets in the cares of the day the weariness of the night season, and so, with lessening power and growing burden, he pursues his purpose.  At last come certain new symptoms, such as giddiness, dimness of sight, neuralgia of the face or scalp, with entire nights of insomnia and growing difficulty in the use of the mental powers; so that to attempt a calculation, or any form of intellectual labor, is to insure a sense of distress in the head, or such absolute pain as proves how deeply the organs concerned have suffered.  Even to read is sometimes almost impossible; and there still remains the perilous fact that under enough of moral stimulus the man may be able, for a few hours, to plunge into business cares, without such pain as completely to incapacitate him for immediate activity.  Night, however, never fails to bring the punishment; and at last the slightest prolonged exertion of mind becomes impossible.  In the worst cases the scalp itself grows sore, and a sudden jar hurts the brain, or seems to do so, while the mere act of stepping from a curb-stone produces positive pain.