Not only the predisposition to sexual desire is congenital, but the enfeebled nervous system that can endure only a limited amount of sexual indulgence. They learn to indulge the sexual appetite at a very early period, and the males grow up effeminate, or half-sexed. The tendency of civilization is toward brain and mental culture. In this we have a cause of nervousness which is wonderful. Our ancestors, who knew very little of brain-work compared to the cramming of the present day――compared to the curriculums of our present school system――were not nervous; they were not excitable, but physically strong. They labored at a variety of toils without machinery, and they obtained physical endurance. Now, the boy is crammed at school and hurried through to professional studies, when he has but just begun life; or he is placed at business, to find that excitement of competition which is the greatest brain-stimulus and the greatest cause of nervousness of the present age. The multitude of collateral sciences that a young man is compelled to read; the books, scientific and novel, that must be perused by every popular student; and the short period of time in which he is expected to pass over this entire field: all tend to change the young man into a habit of nervousness which would surprise our ancestors of one hundred years ago. The labor that was performed by hand by our ancestors, which was the cause of their physical endurance, is now entirely accomplished by machinery; and the modern man, instead of patiently doing the labor by hand, expends months and years at brain-work, attempting to construct a machine that will run by steam, water, or horse-power, that he may save physical force, time, and perhaps, in the end, money. The haste in which Americans live and move, must also become an exciting cause of nervousness. The ancients were patient in obtaining information; in performing works of art, literature, or agriculture. The Greeks did not expect to become proficient in the varied vocations until middle life; but an average American is expected to finish college at twenty-two; to have invented some kind of a machine for the saving of labor, to have made a fortune, married and raised a family of children, wasted his father’s fortune, and be prepared to begin life anew by the time he is thirty years of age. Then, to answer the question, “Why are American people so nervous?” we have but to compare the present with the past; our country with others. The nervousness and mental development of our people, preclude anything but moderation in sexual indulgence; and whenever fast living, brain-working, nervous people indulge to satiety in sexual pleasure, they are in danger of grave consequences, such as our ancestors never knew of, as the results of excessive sexual indulgence. They could cohabit _ad libitum_, and never notice such consequences as nervous people are constantly suffering. CHAPTER II.