nautical skill; nor, lastly, a fertile soil and abundance and variety of mineral riches, a correspondent skill in the general arts of life. In every instance it may be presumed that civilization must have advanced sufficiently to have produced many artificial wants, before individuals feel that powerful stimulus which prompts them to take the full advantage of those resources which nature has placed within their reach. The miserable natives of New Holland, though inhabiting a country as extensive, and in parts as fertile as Europe, have afforded no indications of an approach towards that degree of civilization which would lead them to discover and apply its resources.

But, though it would be a vain and useless speculation to inquire in what way the arts and sciences actually arose, or how it has happened that they were more or less successfully cultivated by different nations, it cannot be either uninteresting or uninstructive to compare the progress which natural science had made in Europe, at a period shortly antecedent to the Christian era, with the state in which it now exists: and such a comparison is in strict accordance with the original intention of this treatise. The materials for this comparison, which will be attempted only on a plan the most general, have been principally derived from Lucretius, and from that work of Aristotle which is entitled, Περὶ Ζώων Ιστορίας. It should be remembered, however, that there is a broad line of distinction between the mode in which natural science was cultivated by the ancients, and that which has been adopted by the moderns. The ancients, though on many occasions as accurate observers of the obvious phenomena of nature as the moderns, were too hasty in coming to conclusions as to the character and cause of those phenomena; and hence the crude opinions and theories with which their philosophy abounded. But, if we justly consider the precept of Thales, "Know thyself," as a precept of the highest wisdom for our moral conduct, we must, on equally strong grounds, consider it as

the highest prerogative of reason, or our intellectual nature, to know the actual extent of its own powers: and it is one of the glories of the phiTosophy of the present day, that, instead of being ashamed of its own limitations, and consequently prone to hurry into unfounded assumptions for the purpose of hiding its ignorance, it explicitly, and at once, acknowledges the point which for the present must be considered as a barrier to further progress; still however looking forward to the period when the increased accumulation of new facts shall enable it to remove that barrier.

SECTION II.

Opinions of Lucretius on the Constitution of Matter in general; and on the Nature of Light, Heat, Water, and Air.

IN attempting to explain the constitution of the universe, and the general phenomena of nature, Lucretius assumes that matter in its primary form consists of very small and impenetrable particles, which, from their supposed incapability of further division, are called atoms; that, from the fortuitous concourse of these atoms, all natural bodies were originally produced; and that into these they are again resolved by those common processes which we are constantly witnessing, as the death and consequent decomposition of vegetables and animals, and the wearing away of the most solid bodies by the effect of exposure to the air, or by the insensible attrition of other bodies: and, lastly, he maintains that these atoms existed from eternity, and are in their essence indestructible.

He asserts as untenable, in fair reasoning, the opinion that there is no term to the divisibility of matter; since, on that supposition, the smallest bodies would consist of an infinite number of parts: and he consequently concludes that those indivisible bodies

or atoms must be perfectly solid.* He impugns, as opposed to common sense, the doctrine of Heraclitus that all things are formed from fire,† and also the doctrine of others, that all things are formed from fire or air, or water or earth; or from binary combinations of them, as of air and fire, or of earth and water: and, lastly, he rejects also the doctrine of Empedocles, that all natural substances are produced from the joint union of fire, earth, air, and water.§ And Lucretius himself supposes that the original atoms of matter may, by a mere variation in the modes of combination, produce all the objects of nature, whether animate or inanimate; illustrating his argument ingeniously by a reference to the fact, that an endless variety of words, of the most different meaning and sound, is produced by various combinations of the same letters. T

It is not necessary, on the present occasion, to comment on the obviously atheistical character of some of the opinions of Lucretius; but it may safely be affirmed, that, although he strains the application of his general argument so as to support a belief in the eternity of matter, denying equally its creation and destructibility; yet the basis of his argument, if confined, as it ought to have been, to the existing constitution of the earth, rests on a legitimate induction from the phenomena of nature: for, certainly, there is no reason for believing that a particle of matter has either been lost or added to the earth or to the atmosphere, since their creation. And, in reasoning from the mere phenomena, Lucretius justly asks, if every thing which disappears, in consequence of age and apparent decay, is actually destroyed, whence is there a renewal of animal or vegetable life? how do rivers continue to flow?** concluding with one of those beautiful illustrations, in which his poem abounds.

Lucret. lib. I. passim. † Lib. I. 636-639, and 691-700. Lib. I. 706-712. § Lib. I. 713-717. Lib. I. 817-829. **Lib. I. 226-232.

"It may be said perhaps, that the showers, which sink into the earth and are lost to our sight, apparently perish: but then, from their fertilizing effects on the soil, and their subsequent incorporation with the growing seed, the harvest rises, and the vine and fig-tree flourish. Hence, moreover, animal life in general derives its support; the sportive lamb hence draws it nutriment from its full-fed mother, and wantons round the meads and woods; and hence those woods themselves yearly resound.with the melody of their native tenants. Nor does the effect stop here: for we ourselves ultimately derive our support from the same source; and cities are eventually peopled from the nutriment produced by the very rain which we had fondly supposed to perish. But nothing really perishes; nature producing new forms of matter, from the materials of those which have apparently been destroyed."*

It would appear, from a very remarkable passage in Lucretius, that some of the philosophers of his day entertained an opinion, which he himself however opposes, that there exists a universal law of gravitation, by which all bodies tend towards the earth as the centre of the universe; that, in consequence of this law, the bodies of those animals which inhabit the opposite, or, as it were, the inferior surface of the earth, are no more capable of falling into the sky which surrounds them, than the animals inhabiting our own, or, the relatively upper surface of the earth, are capable of rising into the sky which is placed above them. And, correspondently with the spherical form of the earth, which almost necessarily follows as a corollary from such an exposition of the law of gravitation, the same philosophers argued that, at the same moment when on the opposite surface it is day, with us it is night.†

Although Lucretius, when speaking in general terms of the tendency of all heavy bodies to fall

* Lib. I. 251-265. + Lib. I. 1051-1065.

towards the earth, and of the acceleration of motion and increase of force which they acquire in falling, offers such an account of the facts as we might expect from his confused doctrine of atoms, and shows his ignorance of the real character of positive gravity; yet of the nature of relative or specific gravity, that is, of the cause why equal bulks of different bodies are of different weights, he gives the true explanation, by asserting that the heaviest bodies contain most matter, and consequently have fewest pores.* That such pores exist not only in wool, and bodies of a similar texture, but even in those which are hard and compact, is proved, he affirms, by the percolation of water through the roofs of caverns; and from the transmission of the food both of animals and plants into their extreme limbs and branches.t

Lucretius considers light as a very subtle kind of matter, which, from its tenuity, is capable of inconceivably swift motion; the rapidity of which motion he instances in its nearly instantaneous diffusion through the whole heaven. With respect to the connexion of light and colour, he not only affirms that the latter cannot exist without the former; but that the particular colour observable in different bodies is not inherent in those bodies, and that in every instance it is produced by the direction, or other circumstances, under which light impinges either on them, or on the eye of the beholder: and he gives as examples the plumage of the neck of the pigeon, and of the tail of the peacock.§ And thus, he adds, the countenances of the audience, and the whole interior of a theatre, closed in with coloured curtains, are tinged with the colour of those curtains. He instances the foregoing position by a reference to the colour of the sea; which, when viewed in the mass,

* Lib. VI. 334-346. and lib. I. 359-370.

† Lib. I. 347-354.

Lib. IV. 184-190, and 200-202.

Lib. IV. 70-78.

§ Lib. II. 794–808.

T