In order to estimate the value of Professor Haeckel's scheme of the universe, it is not necessary to appeal to philosophers: it is sufficient to meet him on scientific ground, and to show that in his effort to simplify and unify he has under-estimated some classes of fact and has stretched scientific theory into regions of guess-work and hypothesis, where it loses touch with real science altogether. The facts which he chooses gratuitously to deny, and the facts which he chooses vigorously to emphasise, are arbitrarily selected by him according as they will or will not fit into his philosophic scheme. The scheme itself is no new one, and almost certainly contains elements of truth. Some day far hence, when it is possible properly to formulate it, a system of Monism may be devised which shall contain the whole truth. At present the scheme formulated by Professor Haeckel must to philosophers appear rudimentary and antiquated, while to men of science it appears gratuitous, hypothetical, in some places erroneous, and altogether unconvincing. Before everything a philosopher should aim at being all-inclusive, before everything a man of science should aim at being definite, clear, and accurate. An attempt at combination is an ambitious attempt, which may legitimately be made, but which it appears is hardly as yet given to man to make successfully. Attempts at an all-embracing scheme, which shall be both truly philosophic and truly scientific, must for the present be mistrusted, and the mistrust should extend especially to their negative side. Positive contributions, either to fact or to system, may be real and should be welcome; but negative or destructive criticism, the eschewing and throwing away of any part of human experience, because it is inconsistent with a premature and ill-considered monistic or any other system, should be regarded with deep suspicion; and the promulgation of any such negative and destructive scheme, especially in association with free and easy dogmatism, should automatically excite mistrust and repulsion. There are things which cannot yet be fitted in as part of a coherent scheme of scientific knowledge—at present they appear like fragments of another order of things; and if they are to be forced into the scientific framework, like portions of a "puzzle-map," before their true place has been discovered, a quantity of substantial fact must be disarranged, dislocated, and thrown away. A premature and cheap Monism is therefore worse than none at all. CHAPTER II "THE LAW OF SUBSTANCE"