It would be extremely surprising if any attempt yet made had already been thoroughly successful, though the attack on the idealistic side appears to many of us physicists to be by far the most hopeful line of advance. An excessively wide knowledge of existence would seem to be demanded for the success of any such most ambitious attempt; but, though none of us may hope to achieve it, many may strive to make some contribution towards the great end; and those who think they have such a contribution to make, or such a revelation entrusted to them, are bound to express it to the best of their ability, and leave it to their contemporaries and successors to assimilate such portions of it as are true, and to develop it further. From this point of view Professor Haeckel is no doubt amply justified in his writings; but, unfortunately, it appears to me that although he has been borne forward on the advancing wave of monistic philosophy, he has, in its specification, attempted such precision of materialistic detail, and subjected it to so narrow and limited a view of the totality of experience, that the progress of thought has left him, as well as his great English exemplar, Herbert Spencer, somewhat high and dry, belated and stranded by the tide of opinion which has now begun to flow in another direction. He is, as it were, a surviving voice from the middle of the nineteenth century; he represents, in clear and eloquent fashion, opinions which then were prevalent among many leaders of thought—opinions which they themselves in many cases, and their successors still more, lived to outgrow; so that by this time Professor Haeckel's voice is as the voice of one crying in the wilderness, not as the pioneer or vanguard of an advancing army, but as the despairing shout of a standard-bearer, still bold and unflinching, but abandoned by the retreating ranks of his comrades as they march to new orders in a fresh and more idealistic direction. CHAPTER IV MEMORANDA FOR WOULD-BE MATERIALISTS The objection which it has been found necessary to express concerning Materialism as a complete system is based not on its assertions, but on its negations. In so far as it makes positive assertions, embodying the results of scientific discovery and even of scientific speculation based thereupon, there is no fault to find with it; but when, on the strength of that, it sets up to be a philosophy of the universe—all inclusive, therefore, and shutting out a number of truths otherwise perceived, or which appeal to other faculties, or which are equally true and are not really contradictory of legitimately materialistic statements—then it is that its insufficiency and narrowness have to be displayed.