Philosophical literature teems with these topics, but it may suffice here to call the attention of the general reader to two or three easily readable summaries--one an explanatory article by Mr. Gerald Balfour, in _The Hibbert Journal_ for April 1910, on the Epiphenomenon controversy, and generally on the alternative explanations of the connexion between Mind and Body, in the light thrown on the subject by Telepathy and Psychical Research; while on the vitality controversy a small book embodying a short course of lectures by the physiologist and philosopher Dr. J. S. Haldane under the title _Mechanism, Life, and Personality_, or a larger book by Professor M'Dougal called _Body and Mind_, may be recommended. On this subject also the writings of Professor J. Arthur Thomson may be specially mentioned. The opinions of the present author on these topics, whatever they may be worth, are held without apology or hesitation, because to him they appear the inevitable consequence of facts of nature as now known or knowable. Some of these facts are not generally accepted by scientific men; and if the facts themselves are not admitted, naturally any conclusion based upon them will appear ill-founded, and the further developed structure illusory. He anticipates that this will be said by critics. In so far as the author's manner of statement is in terms of frank Dualism, he regards that as inevitable for scientific purposes. He does not suppose that any form of Dualism can be the last word about the Universe; but, for practical purposes, mind and matter, or soul and body, must be thought of separately, and it must be the work of higher Philosophy to detect ultimate unity--a unity which he feels certain cannot possibly be materialistic in any sense intelligible to those who are at present studying matter and energy. It may be doubted whether Materialism as a philosophy exists any longer, in the sense of being sustained by serious philosophers; but a few physiological writers, of skill and industry, continue to advocate what they are pleased to call Scientific Materialism. Properly regarded this is a Policy, not a Philosophy, as I will explain; but they make the mistake of regarding it as a Philosophy comprehensive enough to give them the right of negation as well as of affirmation. They do this in the interest of what they feel instinctively to be the ultimate achievement, a Monism in which mind and matter can be recognised as aspects of some one fundamental Reality. We can sympathise with the aim, and still feel how far from accomplishment we are. Nothing is gained by undue haste, and by unfounded negation much may be lost. We must not deny any part of the Universe for the sake of a premature unification. Simplification by exclusion or denial is a poverty-stricken device.