Page:Mind (Old Series) Volume 9.djvu/39



is a proposition very generally accepted by physiologists, that all organic processes could, had we means sufficiently delicate to investigate them, be reduced to series of causes and effects; or, which comes to much the same, that all that ultimate analysis can reveal in these processes, is matter acting as a 'vehicle' of energy. The present article will be devoted to an examination of this proposition in the light of biological facts, and to an endeavour to show that, however great a relative value it may have, it is in fundamental respects inconsistent with these facts.

I shall assume at starting that the proposition just referred to is true, and, as a consequence, use the language of physical science in referring to biological phenomena. I shall then proceed to show that the consistent application to these phenomena of physical conceptions leads to difficulties from which the only escape lies in substituting conceptions and language entirely different, and whose nature will appear in the course of the discussion.2

For physical science a steam-engine is an arrangement of matter into which energy passes from surrounding objects, and out of which, in a different form, the same energy is returned. It will therefore serve the purposes of our discussion to compare a steam-engine so conceived with a living organism. Energy enters the organism in the form of the potential energy which is present in a chemically unstable mixture of oxygen and various forms of food. Similarly the potential energy of an unstable mixture of oxygen and coal enters a steam-engine. From both the steam-engine and the organism this same energy is given off again in the form of heat and mechanical motion. So far the analogy between the steam-engine and the organism is complete.