I began to have headache after every period of intellectual exertion. Then I lost power to sleep. Although I have partially recovered, I am now always warned when I have done enough, by lessening ease in my work, and by a sense of fulness and tension in the head." The indications of brain-tire, therefore, differ in different people, and are more and more apt to be referred to the thinking organ as it departs more and more from a condition of health. Surely a fuller record of the conditions under which men of note are using their mental machinery would be everyway worthy of attention.

Another reason why too prolonged use of the brain is so mischievous is seen in a peculiarity, which is of itself a proof of the auto-activity of the vital acts of the various organs concerned in intellection. We sternly concentrate attention on our task, whatever it be; we do this too long, or under circumstances which make labor difficult, such as during digestion or when weighted by anxiety. At last we stop and propose to find rest in bed. Not so, says the ill-used brain, now morbidly wide awake; and whether we will or not, the mind keeps turning over and over the work of the day, the business or legal problem, or mumbling, so to speak, some wearisome question in a fashion made useless by the denial of full attention. Or else the imagination soars away with the unrestful energy of a demon, conjuring up an endless procession of broken images and disconnected thoughts, so that sleep is utterly banished.

I have chosen here as examples men whose brains are engaged constantly in the higher forms of mental labor; but the difficulty of arresting at will the overtasked brain belongs more or less to every man who overuses this organ, and is the well-known initial symptom of numerous morbid states. I have instanced scholars and men of science chiefly, because they, more than others, are apt to study the conditions under which their thinking organs prosper or falter in their work, and because from them have we had the clearest accounts of this embarrassing condition of automatic activity of the cerebral organs. Few thinkers have failed, I fancy, to suffer in this way at some time, and with many the annoyance is only too common. I do not think the subject has received the attention it deserves, even from such thorough believers in unconscious cerebration as Maudsley. As this state of brain is fatal to sleep, and therefore to needful repose of brain, every sufferer has a remedy which he finds more or less available. This usually consists in some form of effort to throw the thoughts off the track upon which they are moving. Almost every literary biography has some instance of this difficulty, and some hint as to the sufferer's method of freeing his brain from the despotism of a ruling idea or a chain of thought.

Many years ago I heard Mr. Thackeray say that he was sometimes haunted, when his work was over, by the creatures he himself had summoned into being, and that it was a good corrective to turn over the pages of a dictionary. Sir Walter Scott is said to have been troubled in a similar way. A great lawyer, whom I questioned lately as to this matter, told me that his cure was a chapter or two of a novel, with a cold bath before going to bed; for, said he, quaintly, "You never take out of a cold bath the thoughts you take into it." It would be easy to multiply such examples.

Looking broadly at the question of the influence of excessive and prolonged use of the brain upon the health of the nervous system, we learn, first, that cases of cerebral exhaustion in people who live wisely are rare. Eat regularly and exercise freely, and there is scarce a limit to the work you may get out of the thinking organs. But if into the life of a man whose powers are fully taxed we bring the elements of great anxiety or worry, or excessive haste, the whole machinery begins at once to work, as it were, with a dangerous amount of friction. Add to this such constant fatigue of body as some forms of business bring about, and you have all the means needed to ruin the man's power of useful labor.

I have been careful here to state that combined overwork of mind and body is doubly mischievous, because nothing is now more sure in hygienic science than that a proper alternation of physical and mental labor is best fitted to insure a lifetime of wholesome and vigorous intellectual exertion. This is probably due to several causes, but principally to the fact that during active exertion of the body the brain cannot be employed intensely, and therefore has secured to it a state of repose which even sleep is not always competent to supply. There is a Turkish proverb which occurs to me here, like most proverbs, more or less true: "Dreaming goes afoot, but who can think on horseback?" Perhaps, too, there is concerned a physiological law, which, though somewhat mysterious, I may again have to summon to my aid in the way of explanation. It is known as the law of Treviranus, its discoverer, and may thus be briefly stated: Each organ is to every other as an excreting organ. In other words, to insure perfect health, every tissue, bone, nerve, tendon, or muscle should take from the blood certain materials and return to it certain others. To do this every organ must or ought to have its period of activity and of rest, so as to keep the vital fluid in a proper state to nourish every other part. This process in perfect health is a system of mutual assurance, and is probably essential to a condition of entire vigor of both mind and body.

It has long been believed that maladies of the nervous system are increasing rapidly in the more crowded portions of the United States; but I am not aware that any one has studied the death-records to make sure of the accuracy of this opinion. There can be no doubt, I think, that the palsy of children becomes more frequent in cities just in proportion to their growth in population. I mention it here because, as it is a disease which does not kill but only cripples, it has no place in the mortuary tables. Neuralgia is another malady which has no record there, but is, I suspect, increasing at a rapid rate wherever our people are crowded together in towns. Perhaps no other form of sickness is so sure an indication of the development of the nervous temperament, or that condition in which there are both feebleness and irritability of the nervous system. But the most unquestionable proof of the increase of nervous disease is to be looked for in the death statistics of cities.

There, if anywhere, we shall find evidence of the fact, because there we find in exaggerated shapes all the evils I have been defining. The best mode of testing the matter is to take the statistics of some large city which has grown from a country town to a vast business hive within a very few years. Chicago fulfils these conditions precisely. In 1852 it numbered 49,407 souls. At the close of 1868 it had reached to 252,054. Within these years it has become the keenest and most wide-awake business centre in America. I owe to the kindness of Dr. J.H. Rauch, Sanitary Superintendent of Chicago, manuscript records, hitherto unpublished, of its deaths from nervous disease, as well as the statement of each year's total mortality; so that I have it in my power to show the increase of deaths from nerve disorders relatively to the annual loss of life from all causes. I possess similar details as to Philadelphia, which seem to admit of the same conclusions as those drawn from the figures I have used. But here the evil has increased more slowly. Let us see what story these figures will tell us for the Western city. Unluckily, they are rather dry tale-tellers.

The honest use of the mortuary statistics of a large town is no easy matter, and I must therefore ask that I may be supposed to have taken every possible precaution in order not to exaggerate the reality of a great evil. Certain diseases, such as apoplexy, palsy, epilepsy, St. Vitus's dance, and lockjaw or tetanus, we all agree to consider as nervous maladies; convulsions, and the vast number of cases known in the