It will be probably instructive, and it may be sufficient, if I show that two great leaders in scientific thought (one the greatest of all men of science who have yet lived), though well aware of much that could be said positively on the materialistic side, and very willing to admit or even to extend the province of science or exact knowledge to the uttermost, yet were very far from being philosophic Materialists or from imagining that other modes of regarding the universe were thereby excluded. Great leaders of thought, in fact, are not accustomed to take a narrow view of existence, or to suppose that one mode of regarding it, or one set of formulæ expressing it, can possibly be sufficient and complete. Even a sheet of paper has two sides: a terrestrial globe presents different aspects from different points of view; a crystal has a variety of facets; and the totality of existence is not likely to be more simple than any of these—is not likely to be readily expressible in any form of words, or to be thoroughly conceivable by any human mind. It may be well to remember that Sir Isaac Newton was a Theist of the most pronounced and thorough conviction, although he had a great deal to do with the reduction of the major Cosmos to mechanics, _i.e._ with its explanation by the elaborated machinery of simple forces; and he conceived it possible that, in the progress of science, this process of reduction to mechanics would continue till it embraced nearly all phenomena. (See extract below.) That, indeed, has been the effort of science ever since, and therein lies the legitimate basis for materialistic statements, though not for a materialistic philosophy. The following sound remarks concerning Newton are taken from Huxley's _Hume_, p. 246:— "Newton demonstrated all the host of heaven to be but the elements of a vast mechanism, regulated by the same laws as those which express the falling of a stone to the ground. There is a passage in the preface to the first edition of the _Principia_, which shows that Newton was penetrated, as completely as Descartes, with the belief that all the phenomena of nature are expressible in terms of matter and motion:— "'WOULD THAT THE REST OF THE PHENOMENA OF NATURE COULD BE DEDUCED BY A LIKE KIND OF REASONING FROM MECHANICAL PRINCIPLES. FOR MANY CIRCUMSTANCES LEAD ME TO SUSPECT THAT ALL THESE PHENOMENA MAY DEPEND UPON CERTAIN FORCES, IN VIRTUE OF WHICH THE PARTICLES OF BODIES, BY CAUSES NOT YET KNOWN, ARE EITHER MUTUALLY IMPELLED AGAINST ONE ANOTHER, AND COHERE INTO REGULAR FIGURES, OR REPEL AND RECEDE FROM ONE ANOTHER; WHICH FORCES BEING UNKNOWN, PHILOSOPHERS HAVE AS YET EXPLORED NATURE IN VAIN. BUT I HOPE THAT, EITHER BY THIS METHOD OF PHILOSOPHISING, OR BY SOME OTHER AND BETTER, THE PRINCIPLES HERE LAID DOWN MAY THROW SOME LIGHT UPON THE MATTER.'"