"In addition to such wholly separable types of causation, science has still to deal with the interaction of vitalistic and mechanistic causes. It is in the discussion of influences interacting between complex and simple energy units that the greatest confusions and conflicts of scientific analysis arise. For instance, let us suppose that science is called upon to describe the plant growing in a field. It can be shown definitely that the soil is delivering a continuous series of chemical stimuli to the plant. It is equally ascertainable that the plant reacts to these stimuli with a series of reactions peculiar to its own inherent nature. Some of these plant responses will result in the delivery of counter stimuli to the soil and some will not. Those influences which are exercises by the plant over the soil will, for the most part, alter the soil in ways determined by the chemical power of the plant. In so far, therefore, as soil and plant interchange influences, it may fairly be said that the more complex units of energy composing the plant will dominate the interplay of causal forces. But, as we have noted, there will be many changes in the plant, as a result of reactions to soil stimuli, which will not direct any influence back toward the earth. Where these plant changes directed by the soil to its own ultimate benefit, then we might clearly assume that the simpler form of energy was in causal control of the more complex energy unit. That is to say if the soil were able to use the more complex energy of the plant to effect its own enlargement, simply by stimulating the plant to act according to the plant’s own principles of action, we might conclude that, after all, the balance of control lay with the simpler unit of energy. This would amount to the philosophical admission that mechanistic causation holds the balance of power. But such does not appear to be the case. Though stimulated to action by the soil, the plant reacts with its own energy according to its own innate principles of action, and with reaction tendencies designed for its own ultimate benefit. With innate power to develop spontaneously throughout its own life cycle, with a balance of power of interaction capable of changing the soil more radically than the soil can change it, and, finally, with a structure designed in such a way as always to react for its own benefit when stimulated to action by the soil, we are forced to conclude that the plant is a more potent generator of effective causes than the soil."