basis in science than his "atheism"; whether either of them finds any warrant in our knowledge of Nature; whether both may not be equally outside its limits. Most modern thinkers and writers on the principles of science agree in the declaration that the mind of man has not yet attained to knowledge of causes; that it has done no more than to discover a little of the order of Nature.
While we may, if we choose, call the series of events which make up this order a series of effects, nothing seems more certain than that we have not yet succeeded in passing over from them to any reality behind them; that the reason why they occur in one order rather than another is a problem which is as yet absolutely unsolved.
Romanes quotes, with approval which all must share, Tyndall's declaration that "the passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought and a definite molecular action in the brain occur simultaneously, we do not possess the intellectual organ, nor apparently any rudiments of the organ, which would enable us to pass, by a process of reasoning, from the one phenomenon to the other. They appear together, but we do not know why." So far as our present knowledge of the powers of the human mind goes, we must agree with Romanes that Tyndall's assertion is most unquestionably true. Whether or not it is the whole truth is a different question, and we must ask whether we are any more able to pass from one physical event to another physical event, or from one mental event to another mental event, than we are able to pass from a physical to a mental event. Can we say of any of them anything more than that "they appear together, but that we do not know why"?
Romanes tells us that our questions about the nature of the relation between material changes and mental changes admit of only seven possible answers, all of which he enumerates, and four of which we quote: I. The mental changes may cause the material changes (spiritualism). II. The material changes may cause the mental changes (materialism). III. There may be no causation either way, because the association may be only a phenomenal association—the two apparently diverse classes of phenomena being really one and the same (monism). VII. Whether or not there be any causation either way, the association may be one which is necessarily beyond the power of the human mind to explain.
The aim of Romanes's book is to show that six of these seven hypotheses are untenable, and that, since only seven are possible, the seventh, No. III, must be the truth; although it is clear that, if the human mind has as yet discovered nothing but the order of Nature, and has not attained to knowledge of causes, there must be still another point of view. We may declare that we know nothing whatever about the matter; not even enough to warrant the assertion that it is necessarily beyond the power of the human mind to explain. Romanes holds that this way of looking at the subject does not deserve to be regarded as an hypothesis at all; but while it may not be an hypothesis, it may nevertheless be that still more stubborn thing, a fact. Those who agree that it is a fact will feel no more vital interest in Romanes's monism than in materialism or idealism or spiritualism, for they will perceive that all these attempts to reach reality by means of our present knowledge of Nature