speculative hypothesis might rank as theory, and where verification was both unnecessary and impossible.

The most striking instance of a scientific man who on entering philosophic territory has exhibited signs of exhilaration and emancipation, is furnished by the case of Professor Haeckel of Jena. In an eloquent and popular work, entitled das Welt-Räthsel, the World Problem, or "The Riddle of the Universe," this eminent biologist has surveyed the whole range of existence, from the foundations of physics to the comparison of religions, from the facts of anatomy to the freedom of the will, from the vitality of cells to the attributes of God; treating these subjects with wide though by no means superhuman knowledge, and with considerable critical and literary ability. This work, through the medium of a really excellent translation by Mr M'Cabe, and under the auspices of the Rationalist Press Association, has obtained a wide circulation in this country, being purchasable for six-pence at any bookstall; where one often finds it accompanied by another still more popular and similarly-priced treatise by the same author, a digest or summary of the religious aspect of his scientific philosophy, under the title The Confession of Faith of a Man of Science.

Professor Haeckel's credentials, as a learned biologist who introduced Darwinism into Germany, doubtless stand high; and it is a great tribute to his literary ability that a fairly abstruse work on so comprehensive a subject should have obtained a wide notoriety, and have been welcomed by masses of thinking readers, especially by many among the skilled artisans, in this country.

From several points of view this diffusion of interest is most satisfactory, since the spread of thought on serious topics is greatly to be welcomed. Moreover, there is a vast mass of information in these writings which must be new to the bulk of the inhabitants of these islands. There is also a great deal of criticism which should arouse professors of dogmatic theology, and exponents of practical religion, to a keener sense of their opportunities and responsibility. A view of their position from outside, by an able and unsparing critic, cannot but be illuminating and helpful, however unpleasant.

Moreover, the comprehensive survey of existence which can be taken by a modern man of science is almost sure to be interesting and instructive, when properly interpreted with the necessary restrictions and expansions; and if it be found that the helpful portions are unhappily accompanied by over-confident negations and supercilious denials of facts at present outside the range of orthodox science, these natural blemishes must be discounted and estimated at their proper worth; for it would be foolish to imagine that even a diligent student of Nature has special access to the kind of truths which have been hidden from the nominally "wise and prudent" of all time.

So far as Professor Haeckel's writings are read by the thoroughly educated and well-informed, they can do nothing but good. They may not, indeed, convey anything particularly new, but they furnish an interesting study in scientific history and mental development. So far, however, as they are read by unbalanced and uncultured persons, with no sense of proportion and but little critical faculty, they may do harm, unless accompanied by a suitable qualification or antidote, especially an antidote against the bigotry of their somewhat hasty and scornful destructive portions.

To the intelligent artisan or other hard-headed reader who considers that Christian faith is undermined, and the whole religious edifice upset, by the scientific philosophy advocated by Professor Haeckel under the name "Monism," I would say, paraphrasing a sentence of Mr Ruskin's in a preface to Sesame and Lilies:—Do not think it likely that you hold in your hands a treatise in which the ultimate and final verity of the universe is at length beautifully proclaimed, and in which pure truth has been sifted from the errors of all preceding ages. Do not think it, friend: it is not so.

For what is this same "Monism?"

Professor Haeckel writes almost as if it were a recent invention, but in truth there have been many versions of it, and in one form or another the idea is quite old, older than Plato, as old as Parmenides.

The name "Monism" should apply to any philosophic system which assumes and attempts to formulate the essential simplicity and oneness of all the apparent diversity of sensual impression and consciousness, any system which seeks to exhibit all the complexities of existence, both material and mental—the whole of phenomena, both objective and subjective—as modes of manifestation of one fundamental reality.

According to the assumed nature of that reality, different brands of monistic theory exist:—

1. There is the hypothesis that everything is an aspect of some unknown absolute Reality, which itself, in its real nature, is far beyond our apprehension or conception. And within the broad area thus suggested may be grouped such utterly different universe-conceptions as that of Herbert Spencer and that of Spinoza.

2. According to another system the fundamental reality is psychical, is consciousness, let us say, or mind; and the material world has only the reality appropriate to a consistent set of ideas. Here we find again several varieties, ranging from Bishop Berkeley and presumably Hegel, on the one hand, to William James—who, in so far as he is a monist at all, may I suppose be called an empirical idealist—and solipsists such as Mach and Karl Pearson, on the other.

3. A third system, or group of systems, has been in vogue among some physicists of an earlier day, and among some biologists now; viz., that mind, thought, consciousness are all by-products, phantasmagoria, epiphenomena, developments and decorations, as it were, of the one fundamental all-embracing reality, which some may call "matter," some "energy," and some "substance." In this category we find Tyndall—at any rate the Tyndall of "the Belfast address"—and here consistently do we find Haeckel, together with several other biologists.

This last system of Monism, though not now in favour with philosophers, is the most militant variety of all; and accordingly it has in some quarters managed to obtain, and it certainly seems anxious to obtain, a monopoly of the name.

But the monopoly should not be granted. The name Materialism is quite convenient for it, just as Idealism is for the opposing system; and if either of these titles is objected to by the upholders of either system, as apparently too thorough-going and exclusive, whereas only a tendency in one or other direction is to be indicated, then the longer but more descriptive titles of Idealistic-monism and Materialistic-monism respectively should be employed. But neither of these compromises seems necessary to connote the position of Professor Haeckel.

The truth is that all philosophy aims at being monistic; it is bound to aim at unification, however difficult of attainment; and a philosopher who abandoned the quest, and contented himself with a permanent antinomy—a universe compounded of two or more irreconcilable and entirely disparate and disconnected agencies—would be held to be throwing up his brief as a philosopher and taking refuge in a kind of permanent Manichæism, which experience has shown to be an untenable and ultimately unthinkable position.

An attempt at Monism is therefore common to all philosophers, whether professional or amateur; and the only question at issue is what sort of Monism are you aiming at, what sort of solution of the universe have you to offer, what can you hold out to us as a simple satisfactory comprehensive scheme of existence?

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