Closely allied to the claim of the 'mystic' that his experiences bring him into touch with a world of super-sensuous reality, is the attempt to prove that science is incapable of dealing with anything but "in the first place, the endless ascertainment of facts and the physical conditions under which they occur, and in the second place to the criticism of error." Well, no one denies that it is part of the work of science to ascertain facts, or even that its work consists in ascertaining facts and framing 'laws' that will explain them. But why are we to limit science to _physical_ facts only? All facts are not physical. If I have a head-ache, the unpleasant feeling is a fact. If I feel hot or cold, angry or pleased, think one thing ugly or another beautiful, my feelings are as much 'facts' as anything else that exists. Nay, if I fancy I see a ghost, or a vision, these also are 'facts' so far as my mental state at the time is concerned. So also are my beliefs about all manner of things, and often the most important facts with which I am connected. Facts may be objective or subjective. They may exist in relation to all minds normally constituted, or they may exist in relation to my own mind only; or, yet again, they may exist only in relation to certain states of mind, but they do not, nevertheless, cease to be facts. Now the business of science is to collect facts--all facts--classify them, and frame generalisations that will explain their groupings and modes of operation. It talks of the facts of the physical world, the facts of the biological world, the facts of the psychological world, and so forth. This last group comprises all sorts of feelings and ideas, beliefs and experiences. Some of these facts it calls false, others it calls true--that is, they are true when they hold good of all men and women normally constituted, they are not true when they hold good of isolated individuals only, and can be seen to be the product of misinterpreted experience, or arise from a derangement--permanent or temporary--of the nervous system. But true or false they remain facts of the mental life. They must be collected, grouped, and explained exactly as other facts are collected, grouped, and explained. They fall within the scope of science, to be dealt with by scientific methods.