But--the indignant reader may be exclaiming--knowing something is not a bodily movement, but a state of mind, and yet you talk to us about sneezing and such matters. I must ask the indignant reader’s patience. He “knows” that he has states of mind, and that his knowing is itself a state of mind. I do not deny that he has states of mind, but I ask two questions: First, what sort of thing are they? Secondly, what evidence can he give me that he knows about them? The first question he may find very difficult; and if he wants, in his answer, to show that states of mind are something of a sort totally different from bodily movements, he will have to tell me also what bodily movements are, which will plunge him into the most abstruse part of physics. All this I propose to consider later on, and then I hope the indignant reader will be appeased. As to the second question, namely, what evidence of his knowledge another man can give me, it is clear that he must depend upon speech or writing, _i.e._ in either case upon bodily movements. Therefore whatever knowledge may be to the knower, as a social phenomenon it is something displayed in bodily movements. For the present I am deliberately postponing the question of what knowledge is to the knower, and confining myself to what it is for the external observer. And for him, necessarily, it is something shown by bodily movements made in answer to stimuli--more specifically, to examination questions. What else it may be I shall consider at a later stage. However we may subsequently add to our present account by considering how knowledge appears to the knower, that will not invalidate anything that we may arrive at by considering how knowledge appears to the external observer. And there is something which it is important to realise, namely, that we are concerned with a process in which the environment first acts upon a man, and then he reacts upon the environment. This process has to be considered as a whole if we are to discuss what knowledge is. The older view would have been that the effect of the environment upon us might constitute a certain kind of knowledge (perception), while our reaction to the environment constituted volition. These were, in each case, “mental” occurrences, and their connection with nerves and brain remained entirely mysterious. I think the mystery can be eliminated, and the subject removed from the realm of guesswork, by starting with the whole cycle from stimulus to bodily movement. In this way, knowing becomes something active, not something contemplative. Knowing and willing, in fact, are merely aspects of the one cycle, which must be considered in its entirety if it is to be rightly understood.