if it would attain to certainty; it too is an organism capable of that development, renewal, and change of structure which enable it better to fulfil its biological function. That very theory of evolution which had at first sight appeared to prove the mechanical method afresh, and to give it a new weapon wherewith to subdue the rebel world of life, helped rather to depreciate its value and to shake its foundations. Regarded in the light of evolution, was the world what the mechanical theory had held it to be, an eternal persistence of unchangeable substances, an eternal repetition of necessary movements subject to unchangeable laws; or was it rather a perennial becoming, an incessant renewal of forms which cannot be foreseen, and which cannot therefore be subject to the rigid necessity of determinism? Is not variability, that is to say, the possibility of the new, presupposed in all evolution? Can the new be confined within the limits of any mathematical formula? How can mechanics, the science of eternal types, mirror the transient life of the real? It is not to the motionless ideas of reason that we must turn if we would sound the depths of being and grasp it in the productive moment of its generation, but rather to the free creations of imagination and energy. Not sub specie aeternitatis, but sub specie generationis is the motto of modern logic.[1]
The researches of psycho-physiology and more especially the analyses of perception, which proved the subjective character of those sensory elements which the mechanical theory had raised to the rank of ultimate reality, contributed largely to the change in the conception of science and of knowledge in general. Are not resistance, space, and time presentations no less dependent on the special physiological structure than sounds, colours, tastes, and smells? What right have we to regard the one class as objective and primary, the other as subjective and secondary? Helmholtz considers that the only distinction which can fairly be drawn between these elements is of a practical kind,
- ↑ Dewey, “Does Reality Possess Practical Character?” Essays Philosophical and Psychological in Honour of W. James (London, 1908).
