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THE STORY OF PHILOSOPHY
his innermost conviction; leaving it to produce what effect it may. It is not for nothing that he has in him these sympathies with some principles and repugnance to others. He, with all his capacities, and aspirations, and beliefs, is not an accident but a product of the time. While he is a descendant of the past he is a parent of the future; and his thoughts are as children born to him, which he may not carelessly let die. Like every other man he may properly consider himself as one of the myriad agencies through whom works the Unknown Cause; and when the Unknown Cause produces in him a certain belief, he is thereby authorized to profess and act out that belief.…Not as adventitious therefore will the wise man regard the faith that is in him. The highest truth he sees he will fearlessly utter; knowing that, let what may come of it, he is thus playing his right part in the world—knowing that if he can effect the change he aims at—well; if not—well also; though not so well.
IV. BIOLOGY: THE EVOLUTION OF LIFE
The second and third volumes of the Synthetic Philosophy appeared in 1872 under the title of Principles of Biology. They revealed the natural limitations of a philosopher invading a specialist's field; but they atoned for errors of detail by illuminating generalizations that gave a new unity and intelligibility to vast areas of biological fact.
Spencer begins with a famous definition: "Life is the continuous adjustment of internal relations to external relations."[1] The completeness of life depends on the completeness of this correspondence; and life is perfect when the correspondence is perfect. The correspondence is not a merely passive adaptation; what distinguishes life is the adjustment of internal relations in anticipation of a change in external relations, as when an animal crouches to avoid a blow, or a man makes a fire to warm his food. The defect of the definition lies not merely in its tendency to neglect the
- ↑ Principles of Biology; New York, 1910; 1, 99.
