the mind's action therein. On this instant, inevitable inference we believe the proof of the existence of matter to rest, and to rest as securely as if the eye saw it, or the ear heard it, or the hand felt it. Sensation is but the testimony of a faculty, and this unequivocal, constant, reiterated assertion of the mind itself is nothing less.

One of the distinctions of the qualities of matter much insisted on, and made by Hamilton to assume new importance, is that between primary and secondary qualities. The first are those without which matter cannot exist; the second, its variable attributes. Hamilton also adds, as another distinction, that the first are objects of sensation, the second of perception. If we apply as above the notion of cause and effect, this second distinction at once disappears, since all attributes or forces of matter are objects of inference, that is, of perception. We believe, also, that there is no ground for the first distinction. The qualities usually given as primary, are extension and solidity. Now extension in the abstract does not belong to matter. If it is regarded at all as a quality of matter, it can only be so in some specific, evervarying, concrete form. Extension as a quality of a rock before me is not the same as that which belongs to the fragment in my hand. Extension in the abstract is not a quality of anything; for an abstract quality, that it may be abstract, is distinguished from every special manifestation of it. The ball has a certain extension, and certainly no other extension as a quality can be affirmed of it. But this extension which belongs to it cannot, if we accept it as a quality, meet the criterion of primary qualities, that they are necessary to the very existence of matter. The ball might be larger or smaller and still retain its being. But we think that use of language bad and deceptive which speaks of extension as an attribute of matter. It is no more so than time. Why do we not enumerate duration as well as extension among primary qualities, since some portion of time, equally with some part of space, is a condition of the existence of anything? The relation which duration and

extension actually sustain to matter is that of conditions of its existence, not qualities. The qualities of matter, whatever in any given case they may be- and no one collection or bundle of them is necessary as opposed to any other collection or bundle, - require as the antecedent condition of their manifestation both space and time. The actual parts of these in any given case occupied are the extension and duration of the thing considered-relations incident to the manifestation of its qualities, but not the very qualities themselves, nor any portion of them. Eighty cubical inches are not an attribute of the book before me, but extension to that degree is a condition of the manifestation of its attributes, precisely as fifty or one hundred years duration, more or less, are also a condition. The regulative idea of space is disguised under the term "extension," and then referred as a quality to matter, whereas extension, a portion of space, cannot be understood without a prior notion of space, and this constitutes a general condition for all existence.

We will simply add in passing, to prevent confusion, that it has recently been asserted in an able Article in the North American Review that we cannot speak of a portion of space. This we suppose to be true, only as we unite another idea with that of space, namely, that of the infinite. We cannot with propriety talk of a part of infinite space, since a part implies a measured whole, and a whole contradicts the idea of the infinite. This fact, however, does not prevent our employing, with significance and propriety, the term "extension," meaning thereby an area of two or three dimensions in space. Contradiction and confusion creep into language only when such an area is spoken of as a part of space in such a way as to involve the inference of a limited whole.

Passing to the second primary quality of matter, solidity, we find it open to much the same kind of criticism. The solidity of steel and air are very different; there is a force of resistance, but a very diverse force, in each. The precise power of steel is the quality of steel, and this in kind is not requisite to the existence of matter, but only to that particu

lar form of matter known as steel. The abstract quality known as solidity, and supposed to be ever necessary for matter, is in fact found in no one thing, but only some measure of force, some degree of resistance, not necessary to all things, but peculiar to the thing considered. Here, again, a regulative idea has been turned from its precise office, and been attributed to matter. The idea of a cause and of a force are the same. We know both and either

only as the active agent of changes, of effects. But the notion of a resisting force is that of solidity. We attribute solidity to matter, only because it develops under pressure the power or force of resistance. We must remember that solidity as a primary quality of matter is an ambiguous word, that it is not opposed to fluidity, but to what may be called compressibility. A body when confined that it may be a body, must show some measure of incompressibility. The piston must not sink in the cylinder containing it without resistance. Now this force of resistance, some measure of which must belong to all matter, that it may show itself as matter, is an inference under the idea of causation, is supplied by the mind as the source or cause of those permanent phenomena which belong to matter. It is not, therefore, so much a quality of matter-one among the many effects produced by matter, and lodged as sensations in some of our various organs—as it is matter itself, inferred from the qualities we have observed. We give more prominence to this notion of resistance because it responds to our last and most scrutinizing search after the subtiler forms of matter. We may infer a force equally from sight, hearing, smell, taste, but these being intermittent phenomena, depending on the presence of certain conditions, do not serve as final tests of the presence of matter. The force of resistance, however, we should remember, is not a matter of sensation, nor frequently even directly inferable from sensation. Solidity, as opposed to perfect fluidity, we test at once by the muscular sense, but the gases offer no resistance till closely imprisoned, and then not to the hand, except through a sliding-plate or

piston-head. Their resistance, then, is most manifestly inferred through a series of phenomena in which sight and muscular effort take part, and many judgments are involved. It is plainly absurd, then, in this case to say with Hamilton, that primary qualities are directly known by sensation.

The true statement we deem to be this: that under the notion of cause and effect, the condition of matter is a force, and the conditions of a force are space and time. Dr. Hickok's definition of matter, that it is a space-filling force, arises under a rigorous and correct use of regulative ideas. As the notion of causation leads us to the idea of matter, it would seem alone capable of guiding us to a conception of its nature. All that we know of it in itself is, that it is the source of our sensations; and as these imply the action of force or forces upon us, that matter is the permanent centre or source of these forces. We are herein guided to a notion of matter which makes it active rather than passive, a perpetual exertion of power. As in the explanation of mental action, we have been misled by the analogies of matter, so in this instance our conception of physical existence has been unfavorably affected by our knowledge of mental states. In these, as far as the will and the mental, muscular action consequent thereon are concerned, there is a series of active and passive states. Repose, a relatively passive condition, seems to be that into which our activities are constantly lapsing, constantly returning. It is to this condition of rest, revealed in consciousness, that we are disposed to resemble the states of matter; and its mere existence therefore does not impress us with a sense of power: A steam-engine in full operation, strained to its utmost limit, the steam hissing with serpent tongue from every crevice, gives an impression of great forces, yet these forces were just as truly in the iron and the brass, just as active there before they were subjected to this strain as after. Matter presents the equilibrium of intense action; it is the interlock of tremendous powers, and a conception of causes, arrived at legitimately in sole and single view of the effects which express them, would lead us

to conceive matter as a permanent putting forth of unmeasurable power. We need force, great force, and nothing but force, to explain the phenomena of the external world, its gravitation, cohesion, chemical affinities, thermal effects. Whatever other conception we strive to form of matter, we must from it develop these forces, and find no use for anything beyond them. Hence the necessary, and no more than necessary, notion of matter, is that of force or forces in the constant creation of its phenomena.

We have dwelt on this idea of matter as developed by causation, because it has important bearings on philosophical problems. Martineau, one of the ablest of the intuitive school, suggests that matter in its primary qualities may be eternal, and that the wisdom and government of God are shown in its secondary qualities, and in its arrangements. We remember also, that from Plato down, the eternity of matter has often seemed an admissible concession. Under the notion of causation we believe it to be wholly and absolutely inadmissible, and that such a surrender would ultimately bring with it the entire independence and selfexistence of the physical universe. How the primary qualities of matter, so-called, can exist without the secondary, is certainly a mystery; and if we accept what has been said above, that primary qualities merely mark the general conditions of every form of actual matter, that they should so exist we shall regard an impossibility. We must have concrete, actual matter or nothing, and whatever the form of this matter solid, liquid, gaseous, or more elementary than anything yet known-it must still possess forces, and these must have their laws, and therein the seed-germ of the universe may be found independently of God. Matter can mean nothing without the qualities of matter, and these qualities are the expression of forces, and these forces, as now locked in the various kinds of matter, are able under their own laws to initiate a universe. If, therefore, matter itself does not require a God, what in the physical creation does require him? Must we be left to the establishment of special providences in order to prove the being of a God?