"[P]hysical scientists who desire, unselfconsciously, to uplift their fellow humans, endure with difficulty the thought that the destiny of mankind rests supinely in the power of the unbound electron. Mechanistic determinism is abhorred just as whole-heartedly by many a man of letters who sees no logical escape from its tentacles, as it is by “fundamentalist” preachers who see in the triumph of materialism a prospective loss of their own bread and butter. Most dreaded of all mechanistic tenets, apparently, is Darwinian evolution. That monkey has made man in his own image is felt to be a degrading thought. Why? Because such a conclusion is taken to taken to mean that man, once made, continues to be controlled by the same elementary forces which originally produced him. But biological evolution, even if true, entails no such implications. Monkey (or the common ancestor), may have caused man to evolve into his present form ; but man, on the other hand, can now create new types of monkeys at will, by exercising a controlling influence over their breeding habits. And this is the very type of causation idealized by the vitalists. Man, the complex, sets causes in motion which influence the nature of monkey, the simpler animal. Moreover, while the materialistic supposition that monkey originally created man is beyond our present powers of verification, the influence exercised by man over monkey can be observed, any day, in the laboratory. In this argument, at least, we must concede that the vitalists’ variety of causation is more solidly upheld by facts than is the mechanistic type of cause raised by materialists to epic grandeur in the sage of biological evolution. We must admit that while the vitalists begin their theorizing with fictional flights, the materialists conclude their doctrines with an almost equally speculative sublimation of their underlying emotional set. Also, in justice to both, it may be said that the vitalistic account of causation is just as much an accurate observation of physical fact, as is the mechanistic account. Simpler energy units constantly influence more complex units and may, under favourable conditions, control their behavior, while more intricate assemblages of force, by virtue of new attributes derived from their complexity, as constantly compel compliance from cruder types of matter, and do, under our very eyes, completely regulate the simpler energy forms. Physical science must and does include both mechanistic and vitalistic types of causation."