As to mental manifestations, this author says they are extremely variable, insidious, and have a very wide latitude. The vitality of the mind should be far greater than that of the body. Old age dulls conscience, may bring vanity and new ambitions, petulance, irritability, misanthropy, and slows down activity. But the best average barometer of mental failure is memory, the loss of which comes as an advance guard of many symptoms. The old have no faith in the young, for example, Virchow and Agassiz would not accept evolution. There is a universal tendency to overeat, although we should “descend out of life as we ascended into it, even as to the child’s diet.” The first sign that food must be reduced is increased blood pressure. If only lower ideals were exercised in early life, the reversion is ominous. Age is never chronological except in the legal sense. It is often called a vascular problem. The old have immunity from certain diseases such as eruptive fevers, typhoid, phthisis, and old tissues do not seem to be good media for these disease agencies, but age is very prone to pneumonic infections and erysipelas. As to premature senility, in general its symptoms are identical with those of mature senility. The old are particularly prone to flush under very slight emotional strain and cannot throw off care or control patience. As to the causes of premature senility, abuse rather than use is the key. There is an unhealthy tendency to force decline by overtaxing the body and the nerves. It is those who do this who take the pace that kills, taxing themselves beyond their capacities. Alcohol and syphilis are specific forerunners of arteriosclerosis but overeating is worse than alcohol, especially of meat. “Most people eat about twice as much as they need, and the high cost of living is the high cost of overeating.” The dietitian’s table of food values should always be consulted but there has to be wide latitude for individual adjustments. Modern efficiency ideals bring high pressure. Change is the greatest regulator. We now relegate older men to innocuous desuetude to give the younger a chance to forge ahead. As to the proper sphere of the aged, there have been opposite views. Perhaps there are no more than five hundred really great men in history who were clearly above mediocrity. Galton thinks 70 per cent of their work was completed before 45, and 80 per cent before 50. Dorland analyzed four hundred celebrities and concluded the average age of the commencement of their activities was 24 years--in musicians perhaps as early as 17 and scientists at 32. Science is hard and requires a large fund of experience and knowledge. The greatest average for activity in all endeavors together is about 40. To enjoy life after 40 one must have attained some degree of success, for the saddest thing is to reflect on many years of effort and no accomplishment.