Mental exertions produce a great afflux of blood toward the brain each time, with deep thinking more blood arrives to the brain and it is therefore not surprising, as I show in my book on “Human Intellect and its Improvement through Hygienic and Therapeutic Measures.” Such an appalling number of prominent brain workers, men of science and of business, are suffering from hardening of the brain-vessels and are struck by apoplexy of the brain, sometimes even at early ages, before or shortly after their fiftieth year. Indeed a vast majority of the great men of science and business are thus afflicted, as I show in this book, apoplexy being very frequent amongst them. It is reckless overwork, unhygienic methods of mental work that may with surety produce a hardening of the arteries of the brain. It would exceed the short space allowed to this chapter if I should enter here upon the hygienics of mental work, which I am treating in several chapters of my book on the “Human Intellect,” but it will suffice here to emphasize the necessity of interpolating resting days between days of mental overexertion. It would be too much for me to demand that a successful man of business retire entirely from his affairs, but what he could do, especially if the head of the business, is to leave the city on Saturday for the country, with the custom of walking about in the fresh air, returning Monday with fresh strength; and, further, to avoid anything that produces high blood-pressure, hill climbing, hot or cold drinks, strong coffee, tea, and above all tobacco, which is one of the very surest means to increase the blood-pressure. There is no condition where smoking can produce such fatal effects as in arteriosclerosis, and especially if the arteries of the brain, as so often in brain workers, are affected. In inveterate smokers, perhaps a few de-nicotinized cigarettes or cigars may be allowed. In place of regular coffee or tea, coffee without caffeine and the Brazilian tea, maté, whose properties I have described in my book on Rational Diet, may be allowed, but also not in indiscriminate quantities. If too much of them is taken, they may prove not less harmful, therefore also caffeine-free coffee and maté should be taken with wise moderation. Against the troublesome symptoms of arteriosclerosis of the brain like dizziness, loss of memory, difficulty of reasoning, headaches, feeling of pressure upon the brain, etc., I have seen, as I described in special chapters of my book “The Human Intellect,” very good results through the combined use of preparations of iodine and extracts of the thyroid gland. The dizziness disappeared and also the headaches, the memory got much better and also the reasoning power. These effects were, however, obtained in cases not too advanced. As a preventive against arteriosclerosis of the brain and as a remedy against headaches and feeling of pressure in the head I am recommending snuffing in my book on Intellect, showing that through its