Every living thing, from the ultra-microscopic to the highest and most complex multicellular organism, man included, has only one fundamental tendency, the maintenance and defense of its _individual_ existence. The claim that the individual counts for little or nothing, and that the species is everything, is not true to facts. “Nature cares not for the individual, but for the species” is a glittering generality of a metaphysical character. It is the maintenance of its individual existence and the _struggle for this individuality_ and its preservation, whether in defense or aggression, that form the main object of organic life in all its aspects. _The aim of life activities is the individual, the species is a secondary matter._ It is only when we keep this fundamental truth in mind that we begin to understand life in general, and human life in particular. The struggle for existence of which so much is heard in modern science, theoretical or applied, means really the preservation of the individual organism, or the self-preservation of individuality. We may say that the _struggle for existence in the biological and social worlds means nothing else but the Struggle for Individuality_. Wherever the organism forms a whole as to its vitality, whether it be an amoeba or a man, the struggle is for the maintenance of that whole or of that particular individual organism. All the structures and functions go to the preservation of that individuality, or of that individual organic self, constituting the impulse of self-preservation in the total activity of the particular individual organism. The great number of physico-chemical and mechanical processes, adaptations and adjustments of inner structures and functions, as well as the different reactions to the stimuli of external environment, even in the lowest of micro-organisms, are for the _whole_ of the individuality. When organisms take to forms of social life the fundamental aim is still the protection or self-preservation of the individual. The community is an additional defense of the individual against a hostile environment. Thus the herds of Damara cattle, or of social aggregates of other animals, offer greater protection to each individual animal. The individual wolf running in packs has more power for attack and defense. The individual man has more forces for aggression and for protection by living in a social medium which provides the individual with more sensory organs for observation of danger and with more organs for defense and attack, than in isolated states. The herd, the pack, the horde, the society are for the self-preservation of the individual.