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and conditioned to fitting circumstances; both of them imply that which is permanent and necessary. From taste as from touch, we may infer an external, local cause, a cause that must hence occupy space, be a space-filling force, at least to one sense, which is the entire conclusion derivable from resistance.

If it be said that the circumstances are in all cases possible under which the quality of solidity may be drawn out, while those which disclose odor are peculiar to a few bodies, we answer, this is a question of experience, is far from being proved, as in the case of ether, and, if established, could bring with it no sense of necessity, differencing the two cases. Bodies which yield no odor under one form, may under another. Odor seems to involve chemical change, and it might be found that every substance would yield it under fitting chemical conditions. This is a question to be decided by protracted and varied experience, and however decided, could only be the ground of an empirical, and not of a necessary division of qualities.

Take such a secondary quality as that of color. It seems antecedently probable, that all bodies have color. Some gases are apparently colorless, but so is the atmosphere in small volumes. Experience and theory would lead us to expect that the most diffused force in sufficient volume would affect the transmission of light.

These criteria, then, cannot be the sufficient and prevailing ground of this distinction, but we must look farther for something thought to inhere in the very nature of matter, necessary to it and betrayed by every primary quality. This necessary something we accept, and believe the notion of it to arise under the intuitive idea of cause and effect; but also believe, that this notion is called forth, as certainly by odor, by color, by taste, as by pressure; and that we inevitably put back of each of these subjective effects, a permanent