206 HOWARD V. KNOX: effect is subsequent to, or at most synchronous with, its cause ". That axiom is, indeed, purely verbal, so that to deny it would be a self-contradiction. The succession of events, then, that physical science deals with, does not run parallel with the series of mental phenomena. Thus we have to distinguish between the stream of conscious- ness, and the course of physical events as these are thought by us. The existence of physical science is an index, not of the presence, but of the absence of routine in perceptions. Before proceeding to enforce this point, we shall do well to obviate one or two possible misconceptions which might arise as to the nature of the distinction which it is sought to establish. " When," the reader may object, " we ascribe physical effects to causes which fall outside our actual experience, all that we mean is that under such-and-such conditions we should have experienced such-and-such sensations. Consequently we are by no means compelled to the idea that these events really existed in themselves." To which the reply is that at present all this may well be granted, for the sake of argument though later w r e shall have something more to say on this same head. At the present stage of our inquiry, we are not called upon to draw from the necessity of the distinction in question any conclusion as to the ' reality ' of an external world. It is only with the reality of the distinction that we are here concerned. We may describe it for the present, if we like, as a dis- tinction between the course of mental phenomena as they actually occur, and their course as they would occur, or would have occurred, under certain conditions. 1 There is a second possible misconception that has to be guarded against. The distinction under discussion is closely connected with another, which, in its own place, is no less important ; 2 but we must be careful to keep the two apart. This other distinction is the one drawn between events as they appear to us, and the mode in which they are thought of as happening in themselves ; or between our actual perceptions, and explanations (in Professor Pearson's phraseology, descriptions) of these after the manner of what have been called "representative fictions ". Such are the explanations of the phenomena of light by the 1 Though, as will subsequently be shown (part ii.), this is not strictly .accurate, it is sufficiently near the truth for our immediate purpose. 2 It is, in fact, essentially a refinement (as we shall see presently) on ihe general distinction immediately under discussion.
