What distinguishes man most essentially from the other animals, even the most advanced, is his capacity for perfection, which in the lower animal can be paralleled at best by its capacity for _self-preservation_. While the organization of the animals within the short period of which we have any historical knowledge has to all appearances remained essentially unchanged, the world of mankind has changed in quite a remarkable way. This change consists in an increasing subjection of the external world to human purposes, and rests upon the increasing socialization of his capacities. Memory and heredity (the latter being but an extension of memory to the offspring, which is to be conceived of as a part of the older organism) secures in the first place only the preservation of the stock and the renewed development of the new individual in the average type. If a specially favored individual succeeds in accomplishing greater achievements, he may in favorable circumstances transmit this capacity for higher attainments to his offspring. But such individuals gain an advantage in the struggle for existence only if the other sides of their activity do not suffer curtailment as a result. With the limited amount of energy at the individual's disposal every extraordinary accomplishment involves a corresponding _one-sidedness_, and as soon as a certain measure is slightly overstepped, it will cause a reduction of the other functions which will render the individual less fit in the struggle for existence. But this is true only so long as an individual must live _by himself_. As soon as he forms part of a social organization which benefits by his particular activity, the organization compensates for the personal disadvantages by its collective activity, and a social community not only finds room for such special developments, but it even encourages and promotes them. We have already seen that such manifestations occur within the organism itself. Higher functions, depending upon the higher susceptibility of the sense organs, can only be attained at the expense of the general functions by the organ in question. We observe this fact in all socially organized beings, like bees and ants, which display a high degree of specialization in the functions of the individual subordinate groups; the specialization often being carried so far that the individual groups can no longer subsist by themselves alone. It is only the organization as a whole that is capable of permanent existence.