In looking on physical nature, as far as our object is concerned, little is got in Aristotle, the idea of which did not exist elsewhere. His first form of substance, which is perceptible to the senses, is finite and perishable; he uses the ordinary four elements. There is a fifth element preceding the four elements, with a tendency neither above nor below; this is ether. The heaven is made of it, and never changes. The four elements seem to be substance united to the warm, the cold, the light, and the heavy.* He more clearly brought forward existing theories, expressing his own with greater care, and giving a history of others.

The varying phases of matter and of force shewed themselves in after philosophies. Matter rose and fell, mind rose and fell. Matter was mind, mind was matter, and even at this period we see no such nice distinction between them among the ancients as we now have, whatever be the foundation of our opinions.

The stoics said, that "matter (that is; considered in itself without quality and form) did not exist except under a certain form, and with certain properties. It is the principle of every thing which springs from it, and consequently is variable. Being absolutely passive it is infinitely divisible as body is." But these opinions would lead into grounds too

little physical.

The stoics retained the four elements which lasted so long in science, and believed that fire was condensed into air, air into water, water into earth. They called matter a collection of dimensions, length, breadth and thickness, leaving out solidity, so that matter became penetrable. Only matter can do any thing. This led to the wildest assertions, that laughing, dancing, walking, crying, as well as emotions, anger, joy, fear and passions, avarice, pride and envy, vices and virtues, day, night, and sound, were bodies. This was carrying

* Tiedemann, Vol. II, p. 284. † Ritter, p. 479. Tiedemann, p. 434.

out their general principle to the utmost, and, of leads to an entire want of definition of natural Knowledge is gained by observing qualities, not founding them; by seeing distinctions, not by hidin The most contradictory assertions of all kinds ha made on the subject, especially after the great mas done their utmost services. We must not suppose th to be merely ridiculous. It evidently involves an e of the idea of body, the limits of which are still u and in some form or other it has often risen, and again to rise, for discussion.

We find that ir. nearly all the cases alluded to ma been able to put on various forms, and that it is a mere abstraction. There is, in nearly all, a sub more or less decidedly expressed. That is, a matter properties to the senses, but capable of putting on all mater, mother of all substances. With this idea bef most of the opinions will have some connection and ality. Among those who denied the existence of the in the things perceived by the senses, we can find ver directly relating to the subject; but we must ever vie admiration and gratitude the acute minds which have d much of the preliminary work necessary both for physi philosophy.

The atomic system of the ancients was most full plained by Lucretius, and leaving the nice distinctions stoics, and their semi-metaphysical modes of looki matter, let us look more fully at this system than the o as it may be said to form the beginning of the atomic th although the short and meagre introduction preceding not be without interest to such as have not had time to of the struggles of the mind in early times towards a ra expression of phenomena. It was a struggle of the gifted minds in some of the most brilliant days of the w

and will never cease to be an interesting chapter in man's history.

The more distinct conceptions of matter introduced by Leucippus, and promulgated by Democritus, were adopted by Epicurus, and have often gone by his name. If not ultimately the most exact, they have in many respects a practical truth, and they have the merit of having the main features clearly intelligible. The system was gaining ground at a time when the Alexandrian school was saying that matter which can be perceived emanates from the soul,* and that bodies were convertible into each other because made of one matter, which original matter had no qualities, and was capable of taking all. This was very much in the manner of their predecessors, except that we recognise in it an increase of mysticism in their expressions. This substratum of matter has bewildered whole tribes of philosophers.

Lucretius is in the hands of every one, but read by few. The following portion on atoms is from the translation of the Rev. J. S. Watson (Bohn), with little alteration :—

*

"Nothing can do or suffer without bodily substance, nor, moreover, afford place (i. e., for acting and suffering) except empty and vacant space. No third nature, therefore, (distinct) in itself, besides vacant space and material substance, can possibly be left in the sum of things; no third kind of being, which can at any time affect our senses, or which any one can find out by the exercise of his reason.‡ Bodies are partly original elements of things, and partly those which are formed of a combination of those elements. But those which are elements of things no force can break, for they successfully resist all force by solidity of substance; although, perhaps, it seems difficult to believe that anything of so solid a substance can be found in nature; for the lightning of heaven passes through the walls of houses, as also noises and voices pass;

* Ritter, Vol. IV., p. 488.

Tiedemann, Vol. III., p. 295. See also Histoire de l'ecole d'Alexandrie, par M. Jules Simon. No short sentence can give the exact truth.

N

Book I., 1. 444-449.

iron glows in the fire; rocks often burst with fervent heat; the hardness of gold, losing its firmness, is often dissolved by heat; the icy coldness of brass, overcome by flame, melts; heat and penetrable cold enter into silver, for we have felt both with our hand, when, as we held cups straight in the hand, water was poured into them from above, so that as far as these instances go there is nothing solid in nature. But because, however, right, reason, and the nature of things, compel (me to hold a different opinion,) grant me your attention until I make it plain in a few verses, that there really exist such bodies as are of a solid and eternal corporeal substance, which bodies we prove to be seeds and primary particles of things, of which the whole generated universe now consists."

"In the first place, since a two-fold nature of two things extremely dissimilar has been found to exist, viz., matter and space, in which everything is done, it must necessarily be that which exists by itself for itself, and pure (free from mixture); for wheresoever there is empty space, which we call a vacuum, there is no matter; and likewise wheresoever matter maintains itself, there by no means exists empty space. Original substances are therefore solid, and

without vacuity.

"Furthermore, since in things that are produced there is empty space, solid matter must exist around it; nor can anything be proved by just argument to conceal vacuity, and to contain it within its body, unless we admit that which contains it to be a solid. But that solid can be nothing but a combination of matter, such as may have the power of keeping a vacuity enclosed. Matter, therefore, which consists of solid body may be eternal, while other substances may be dissolved (or cease to be). In addition, too, if there were no space to be vacant and unoccupied all would be solid. On the other hand, unless there were certain bodies to fill up completely the spaces which they occupy, all space which exists must be an empty word. Body, therefore, is evidently distinct from empty space.

"These bodies (which thus fill up empty space) can neither be broken in pieces by being struck with bodies externally, nor again can be decomposed by being penetrated internally; nor can they be made to yield, if attempted, by any other method, which we have demonstrated to you a little above; for neither does it seem possible

for anything to be dashed in pieces without a vacuum, nor to be broken, nor to be divided in two, by cutting; nor to admit moisture, nor moreover subtle cold, nor penetrating fire, by which all things are dissolved; and the more anything contains empty space within it, the more it yields when thoroughly tried by these means. If, therefore, the primary atoms are solid and without void, they must of necessity be eternal.

"Again, unless there had been eternal matter, all things before this time would have been utterly reduced to nothing, and whatsoever we behold would be a reproduction from nothing. But since I have shown above that nothing can be produced from nothing, and that that which has been produced can not be resolved into nothing, the primary elements must be a of an imperishable substance, into which every body may be dissolved, so that matter may be supplied for the reproduction of things. The primordial elements therefore are of pure solidity, nor could they otherwise, preserved as they have been for ages, repair things through the infinite space of time.

"Besides, if nature had set no limit to the destruction of things, the particles of matter would by this time have been so reduced, every former age wasting them, that no body compounded of them could, from any certain time, reach full maturity of existence. For we see that anything may be sooner broken to pieces than put together again; for which reason, that which the infinitely long duration of past time had broken into parts, disturbing and dissevering it, could never be repaired in time to come. But now, as is evident, there remains appointed a certain limit to destruction, since we see every thing recruited, and stated portions of time assigned to every thing according to its kind, in which it may be able to attain full vigour of age.

"To this is added, that although the primary particles of matter are perfectly solid, yet that all things which are formed of them, may be rendered soft, as air, water, earth, fire, because there is vacant space intermingled with the things compounded. But, on the other hand, if the primordial elements were soft, how strong flints and iron could be produced, no explanation could be given, for nature would be deprived of all possibility of commencing a foundation. The primordial elements therefore are endowed with pure solidity;