and that, when it has prospered, it has not been under the shadow of authority, but in the light of reason. It may be true that whenever it has been widely prevalent, moral, social, and political influences have contributed to its diffusion; that interests and passions have often been as helpful to it as reasons. But the same may be said with equal justice of all systems. No doctrine rests exclusively on intellectual grounds, or triumphs merely in the strength of pure reason. Materialism, it cannot be denied, has constantly appealed to reason, and has prevailed most in epochs characterised by activity of reason. It has not faded and decayed, but grown and flourished, with the increase and expansion of scientific light. It was never more prevalent than in the present day, when the spirit of investigation is everywhere obviously and energetically at work.

Materialism could never have thus lasted and flourished had it not been a very plausible theory. It could never have had the history which it has had unless it had much to say for itself. Make full allowance for interests and passions operating in its favour, yet interests and passions can only sustain and propagate either themselves or any doctrine or movement when they are accompanied by the persuasion that reason is on their side. Nothing is more impotent than mere passion-blind passion,-except it be mere interest

-interest consciously separated from or opposed to truth. Materialism must be able to adduce in its favour arguments which are fitted to impress and convince both the popular and the scientific mind. Its claims to acceptance must rest on grounds which, while not recondite or difficult to understand, are yet of a kind calculated to satisfy many intellects which have been disciplined by physical science.

That this is the case I must endeavour to show. It is clearly impossible to examine in a single lecture even a very few of the most celebrated vindications of contemporary materialism, while it would hardly be fair or satisfactory to discuss merely one of them. It seems necessary, therefore, to treat of contemporary materialism, or, as it is sometimes called, scientific materialism, in a general way. This requires that I should begin by indicating as comprehensively as is consistent with brevity the general character of the argumentation which is employed in its support.

In the first place, then, materialism claims to satisfy better than any other system the legitimate demands of the reason for unity. There cannot be more than one ultimate explanation of things. If the variety of existences in the universe are traced back to two or more causes, the intellect must sooner or later perceive that it has stopped abruptly and left its work incomplete. The two

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or more causes which have been reached neces'sarily limit and condition one another. Whence and why are they thus bounded and associated? The question cannot be evaded. Reason demands an answer to it, and no answer can be found in the several finite and co-ordinate causes themselves; it must be found in a single higher cause on which they are dependent. It is only by reaching unity that we can get above the limits and conditions. which are conclusive evidences of dependence. Hence every form of dualism must be rejected as a theory of existence. Only a monistic philosophy can be a true philosophy. But theism, say materialists, is essentially dualistic. It traces the diversity of phenomena in the universe not to one cause, but to two causes. It refers some things to mind, and other things to matter, and maintains that matter and mind are substantially distinct. It leaves us with two principles, and by so doing virtually reduces even the one which it pronounces infinite to something finite, while it renders it impossible for us to conceive of the connection between matter and mind otherwise than as arbitrary. Materialism, on the other hand, is monism. It explains the whole world in terms of matter. It resolves everything in nature-order, organisation, life, sensation, thought, poetry, religion, history-into combinations and motions of matter. It exhibits the universe as a perfectly

homogeneous and coherent system naturally evolved out of a single primary existence. It thus satisfies the demands of philosophy or rational theory for unity. Idealism, it is true, sets up rival pretensions. It professes to start with the selfidentity or absolute unity of thought, and to explain matter as a stage in the development or as a phase of the manifestation of thought. But are not its claims obviously less satisfactory? We know nothing of ideas or thoughts except as states of human consciousness, as affections or products of that in ourselves which we call mind. They are special phenomena in the life or experience of men, and men are themselves only a species of natural existences-a class of animalsapparently the last evolved in the terrestrial sphere of things. Man is included in the universe, and ideas are included in man. Reason consequently requires us to seek the explanation of man and ideas in what is common and primary in the universe-matter and motion. To attempt to explain what is ancient by what is recent, the general by the particular, the macrocosm by the microcosm, universal existence by the modifications of highly specialised organisations, is a monstrous vσrepov рóτEроv, a manifest violation of the laws of scientific method. Thought, which is independent of human consciousness, can only be affirmed to exist by an arbitrary act of the individual mind,

and is no real principle, but a mystical assumption; thought, which is dependent on human consciousness, can no more be the unity which accounts for the universe, than the characteristic features of the leaves of a particular kind of tree can be the sole and adequate explanation of the entire vegetable kingdom.

Further, materialism claims to be the only theory which satisfactorily shows that all things have come to be what they are in a truly natural manner. When describing the evolution of the universe from unity to multiplicity, it appeals to no arbitrary or imaginary factor, no principle which is supernatural, no process which transcends or contravenes science. It represents the universe as a self-consistent and perfect system, in which everything that happens follows necessarily from the powers inherent in the system itself. Theism, on the contrary, supposes that the universe in itself is incoherent and imperfect, and that the explanation of many things in it must be sought for out of itself. It conceives of the matter of the world as created; of its powers as derived; of its order as contrived; and of certain events and existences comprehended in it as produced by special acts of Divine interposition. Such a view, say materialists, is essentially anti-scientific. It implicitly denies not only that the world is a scientific unity, but that its phenomena are expli