another, according to certain laws regulating the intensity. Those centres ought, in this kind of mathematics, to be regarded as points without magnitude. We do not here deny that those powers are the powers of some substance, any more than geometricians deny that figure can exist only in some mass. But we affirm that the substance in which they exist is not known except by its powers, that, therefore, these alone are legitimate objects of inquiry, -and that we must conform our opinion of the substance to what we find its powers actually to be.

These centres of various attractions and repulsions may approach to or recede from one another according to certain definite circumstances, carrying their peculiar spheres of attraction and repulsion along with them. The arrangement, action, and intensity of these powers in their different spheres may be varied indefinitely, so as to correspond to all the kinds of bodies.

A compages of these centres, placed within the sphere of each other's attraction, will constitute a body that we term compact; and two of these bodies will, on their approach, meet with a repulsion or resistance, sufficient to prevent one of them from occupying the place of the other, at least without a much greater force than we are capable of exerting.

In the constitution of all bodies that we are ac

quainted with, these centres are placed so near each other, that, in every division which we make, we still leave parts which contain many of them. But, as the centres constituting any body cannot be supposed absolutely infinite, it must be possible to come ultimately to one single centre not farther divisible.

If two of these centres might be supposed to coincide they would then only form a centre with different powers, those belonging to the one centre modifying those of the other. Or if their powers were the same at the same distances before the coincidence, then after it they would be doubled at the same distance.

This new sort of elementary mathematics, or mode of considering and reasoning upon bodies, does not imply any denial of the existence of other powers in matter besides attraction and repulsion, but merely attends to these abstractly from the others. But, by this mode of considering bodies in their two most essential powers, we see how very different a thing matter is, from what it at first appears, and how absurd it is to assert that all matter is incapable of sensation. For the powers of attraction and repulsion, so essential to the very existence of bodies, are more foreign to our first notions of all matter, than the power of sensation is to our idea of some portions of it.

Thus our views of sensation and perception are

conformable to the discoveries of science, and the testimony of science is reciprocally favourable to our views upon those subjects.

The view of matter here presented was first exhibited by Father Boscovich, at Rome, and is adopted by Dr. Priestley and others in our own nation.

CHAPTER VII.

OF THE INTELLECTUAL FACULTIES.-INFLUENCE OF THE BODY.FEELING OF BODILY LIFE.-MENTAL FEELING OF EXISTENCE. -GRAND GENERAL OFFICE OF THE BRAIN.

HAVING already traced the germ of our mental operations, we proceed to examine the powers of the human mind in their least complicated state. While, however, we treat of these powers separately, let it never be forgotten that no one of them is ever exercised separately from the others. It may be said that there is but one power in the mind, -the power of thought; but for the sake of more fully comprehending the nature of that power, and the modifications of which it is susceptible, it is necessary to view it under several aspects.

We begin with conception, which is naturally the first aspect of the power of thought. Mr. Stewart defines it to be "that faculty of the mind which enables it to form a notion of an absent object of perception, or of a sensation which it has formerly felt." At the same time he observes

I

that conception implies no notion of time whatever; it would appear, therefore, not to be essential to conception that the object of it should be either past or absent. In the preceding chapter I have spoken of it as applied to cases in which the bodily sensation is present. And in this use of the term I may shelter myself by the authority of Dr. Reid, who says that "if we attend to that act of our mind which we call the perception of an external object of sense, we shall find in it these three things: first, some conception or notion of the object perceived; secondly, a strong and irresistible conviction and belief of its present existence," &c.* Here the term conception is applied to cases where the perception is present. And in another place Dr. Reid has the following words: "It may be observed that conception enters as an ingredient in every operation of the mind our senses cannot give us the belief of any object, without giving some conception of it at the same time: no man can either remember or reason about things of which he hath no conception : when we will to exert any of our active powers there must be some conception of what we will to do: there can be no desire nor aversion, love nor hatred, without some conception of the object: we cannot feel pain without conceiving it, though we