phænomenon in nature appears to disprove its existence. The minutest corpuscle we can operate upon is still capable of a minuter division, and the parts into which it divides, possessing the common nature of the corpuscle which has produced them, must necessarily, it is added, be capable of a still farther division; and as such divisions can have no assignable limit, matter must necessarily and essentially be divisible to infinity.

Such was the reasoning of Des Cartes, and of the numerous host of philosophers who attached themselves to his theory about the middle of the seventeenth century. The argument, indeed, is highly plausible; but it was soon obvious, that, like the Grecian incorporeity of matter, it leads to a pure nonentity of a material world: for that which is essentially unsolid and infinitely divisible, must at length terminate in nothing. And hence Leibnitz attempted to amend the system, about half a century, and Boscovich, about a century afterwards, by contending, as, indeed, Zeno is supposed to have done. formerly, that matter has its ultimate atoms, or monads, as they were denominated by Leibnitz, from the language of Pythagoras, beyond which it is altogether indivisible; and that these ultimate atoms or monads are simple inextended points, producing, however, the phænomenon of extension, by their combination, and essentially possessed of the powers of attraction and repulsion.

There is such a charm in novelty, that it often leads us captive in despite of the most glaring errors, and intoxicates our judgment as fatally as the cup of Circe. It is upon this ground alone we can account for the general adoption of this new system,

when first proposed in its finished state by Boscovich, and the general belief that the Gordian knot was at length fairly untied, and every difficulty overcome. It required a period of some years for the heated imagination to become sufficiently cool to enable mankind to see, as every one sees at present, that the difficulties chargeable upon the doctrine of an infinite divisibility of matter are not touched by the present theory, and remain in as full force as before its appearance. If the monads, or ultimate points of matter here adverted to, possess body, they must be as capable of extension, and consequently of division, as material body under any other dimension or modification: if they do not possess body, then are they as much nonentities as the primal or amorphous matter of Plato or Pythagoras. Again, we are told that these points or monads are endowed with certain powers; as those, for example, of attraction and repulsion. But powers must be the powers of something: what is this something to which these powers are thus said to appertain? If the ultimate and inextended points before us have nothing but these powers, and be nothing but these powers, then are such powers powers of nothing, powers without a substrate, and, consequently, as much nonentities as on the preceding argument. Visible or sensible matter, moreover, it is admitted by M. Boscovich and his disciples, is possessed of extension; but visible or sensible matter is also admitted to be a mere result of a combination of inextended atoms:- how can extension proceed from what is inextended?—of two diametrical opposites, how is it possible that either can become the product of the other?

It is unnecessary to pursue this refutation. The lesson which the whole of such fine-spun and fanciful hypotheses teach us, and teach us equally, is, that it is impossible to philosophise without a firm basis of first principles. We must have them in physics as well as in metaphysics,-in matter as well as in morals; and hence the best physical schools in Greece, as well as in more modern times,- those which have contended for the eternity of matter, as well as those which have contended for its creation out of nothing, -have equally found it necessary to take for granted, what, in fact, can never be proved, that matter in its lowest and ultimate parts consists of solid, impenetrable, and m oveable particles of definite sizes, figures, and proportions to space; from different combinations of which, though invisible in themselves, every visible substance is produced.

This theory, which has been commonly distinguished by the name of the Atomic philosophy, was first started in Greece by Leucippus or Democritus, and afterwards considerably improved by Epicurus; and as it bears a striking analogy to many of the features which mark the best opinions of the present day, and has probably given them much of their colour and complexion, if it have not originated them, I shall take leave to submit to you the following outline of it*:

The Atomic philosophy of Epicurus, in its mere physical contemplation, allows of nothing but matter and space, which are equally infinite and unbounded, which have equally existed from all eternity, and

* This outline is given more at length in the author's Prolegomena to his translation of " The Nature of Things," p. cix. and foilowing.

from different combinations of which every visible form is created. These elementary principles have no common property with each other: for whatever matter is, that space is the reverse of; and whatever space is, matter is the contrary to. The actually solid parts of all bodies, therefore, are matter; their actual pores space; and the parts which are not altogether solid, but an intermixture of solidity and pore, are space and matter combined. Anterior to the formation of the universe, space and matter existed uncombined, or in their pure and elementary state. Space, in its elementary state, is absolute and perfect void; matter, in its elementary state, consists of inconceivably minute seeds or atoms, so small that the corpuscles of vapour, light, and heat are compounds of them; and so solid, that they cannot possibly be broken or abraded by any concussion or violence whatever. The express figure of these primary atoms is various: there are round, square, pointed, jagged, as well as many other shapes. These shapes, however, are not diversified to infinity; but the atoms themselves of each existent shape are infinite or innumerable. Every atom is possessed of certain intrinsic powers of motion. Under the old school of Democritus, the perpetual motions hence produced were of two kinds: a descending motion, from the natural gravity of the atoms; and a rebounding motion, from collision and mutual clash. Besides these two motions, and to explain certain phænomena to which they did not appear competent, and which were not accounted for under the old system, Epicurus supposed that some atoms were occasionally possessed of a third, by which, in some very small degree, they descended

in an oblique or curvilinear direction, deviating from the common and right line anomalously; and in this respect resembling the oscillations of the magnetic needle.

These infinite groups of atoms, flying through all time and space in different directions, and under different laws, have interchangeably tried and exhibited every possible mode of rencounter; sometimes repelled from each other by concussion, and sometimes adhering to each other from their own jagged or pointed construction, or from the casual interstices which two or more connected atoms must produce, and which may be just adapted to those of other figures, as globular, oval, or square. Hence, the origin of compound and visible bodies; hence, the origin of large masses of matter; hence, eventually, the origin of the world itself. When these primary atoms are closely compacted, and but little vacuity or space lies between, they produce those kinds of substances which we denominate solid, as stones and metals; when they are loose and disjoined, and a large quantity of space or vacuity is interposed, they exhibit bodies of lax texture, as wool, water, vapour. In one mode of combination they form earth; in another, air; and in another, fire. Arranged in one way, they produce vegetation and irritability; in another way, animal life and perception. Man hence arises, families are formed, societies are multiplied, and governments are instituted.

The world, thus generated, is perpetually sustained by the application of fresh tides of elementary atoms, flying with inconceivable rapidity through all the infinity of space, invisible from their minuteness, and occupying the posts of those that are as per