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mind into the world. This shows us the great value that the biological aspect of the subject possesses for psychology, for economics, and for sociology. It explains the meaning of the law of self-preservation in man. What is this mean- ing?
" Self-preservation is the first law of nature." So runs the adage. And it is true. It is true quite independently of the quality of the life that so much effort is made to preserve. Whether it is worth preserving or not has no bearing upon the result. This is so because man was himself once an animal and knew nothing about death. He then fled from pain as animals do. After his brain had so far developed that he was capable of mentally connecting pain with death and of realizing that to escape pain was to preserve life, the instinct which had brought him through to that state was ineradicably implanted in his nature, and no amount of knowledge or force of reason has ever sufficed to disturb it. By the time he was able to express ideas by oral language so completely had the deriva- tive conception of preserving life supplanted the original con- ception of escaping pain that the latter was lost sight of, and it would be to many today a new thought, while some might even be found to question it.
Here, too, is to be found the true explanation of optimism. It is simply the instinct of self-preservation, a survival of the instinct of pain avoidance, and forms the negative aspect of the primordial psychic factor feeling, which was the essential condi- tion to the origin and development of the entire class of beings that possess it. It is not, therefore, to be expected that anything so deeply rooted in the constitution of organic nature should be affected by the cold calculations of latter-day philosophers who may balance up the debits and credits of life and figure out a deficit. Whether there be such a deficit in animal life, and whether there has been any such in human life thus far, or in any stage or portion of it, it may be impossible exactly to decide, but in any case it is certain that the instinct to escape danger has been successful in tiding man over the prolonged
