The existing anthropoid apes may justly be compared in condition with the existing low savages. In both cases a satisfactory adaptation to their situation has been gained. These apes are still arboreal and frugivorous, as their remote ancestors were. They have for ages been in a state of close adaptation to their life conditions, and the influences of development have been largely wanting. Such evolution as took place must have been extremely slow. In like manner the lowest savages live in intimate relations with the conditions surrounding them. All problems of food-getting, habitation, climate, etc., have long since been solved, and in the tropical forests in which so many of them dwell they are in thorough accord with the situation. Mentally, therefore, they are practically at a standstill and have remained so for thousands of years. The two cases are parallel ones. We can safely say that the later development of man took place in other situations and under other conditions. We may fairly say the same in regard to the ape. Vigorous influences must have been brought to bear upon the ancestor of man as the instigating causes of its mental development into man; and similarly vigorous influences must have been brought to bear upon primitive man to set in train his mental development into intellectual man. And the general character of these influences in both cases may readily be pointed out. An extraordinary development has taken place in the human intellect within a few thousands, or tens of thousands, of years, yielding the difference which exists between the cultivated man of to-day and the debased savage who probably preceded him, and whose counterpart still exists. This has undoubtedly been due to influences of the highest potency. If we can show that influences of equal potency acted upon man's ancestor, we shall have done much toward indicating how the ape brain may have grown into the brain of man. In both cases the main agency was in all probability that of conflict. Both ape and man, as we take it, developed through some form of warfare. In the former case it was warfare with the animal kingdom; in the latter it was warfare with the conditions of nature and with hostile man. Each of these has been potent in its effects, and to each we owe the completion of a great stage in the evolution of man.