by bare soul. Hence a difference, made in one side, must make a difference to the other side, and it makes a difference also to both sides of what follows. And, though this statement will receive later some qualification (p. 337), the causal connection of the soul’s events, in general, is inseparably double.
In physiology and in psychology we, in practice, disregard this complication. We for convenience sake regard as the cause, or as the effect, what is in reality but a prominent condition or consequence. And such a mutilation of phenomena is essential to progress. We speak of an intellectual sequence, in which the conclusion, as a psychical event, is the effect of the premises. We talk as if the antecedent mental state were truly the cause, and were not merely one part of it. Where, in short, we find that on either side the succession is regular, we regard it as independent. And it is only where irregularity is forced on our attention, that we perceive body and mind to interfere with one another. But, at this point, practical convenience has unawares led us into difficulty. We are puzzled now to comprehend how that which was independent has been induced to leave its path. We begin to seek the cause which forces it to exert and to suffer influence; and, with this, we are well on the road to false theory and ruinous error.
But the truth is that no mere psychical sequence is a fact, or in any way exists. With each of its members is conjoined always a physical event, and these physical events enter into every link of causation. The state of mind, or body, is here never more than part-cause, or again more than part-effect. We may attend to either of the sides, which for our purpose is prominent; we may ignore the action of the other side, where it is constant and regular; but we cannot deny that both really contribute to the effect. Thus we speak of feelings and of ideas as influencing the body. And so they do, since they
