Again, in a question concerning mechanical action, he says, "When a man moves a stone by pushing it with a stick, we say both that the man moves the stone, and that the stick moves the stone, but the latter more properly."

Again, we find the Greek philosophers applying themselves to extract their dogmas from the most general and abstract notions which they could detect; for example, from the conception of the Universe as One or as Many things. They tried to determine how far we may, or must, combine with these conceptions that of a whole, of parts, of number, of limits, of place, of beginning or end, of full or void, of rest or motion, of cause and effect, and the like. The analysis of such conceptions with such a view, occupies, for instance, almost the whole of Aristotle's Treatise on the Heavens.

The Dialogue of Plato, which is entitled Parmenides, appears at first as if its object were to show the futility of this method of philosophizing; for the philosopher whose name it bears, is represented as arguing with Aristotle, and, by a process of metaphysical analysis, reducing him at least to this conclusion, "that whether One exist, or do not exist, it follows that both it and other things, with reference to themselves and to each other, all and in all respects, both are and are not, both appear and appear not." Yet the method of Plato, so far as concerns truth of that kind with which we are here

concerned, was little more efficacious than that of his rival. It consists mainly, as may be seen in several of the dialogues, and especially in the Timæus, in the application of notions as loose as those of the Peripatetics; for example, the conceptions of the Good, the Beautiful, the Perfect; and these are rendered still more arbitrary by assuming an acquaintance with the views of the Creator of the universe. The philosopher is thus led to maxims which agree with those of the Aristotelians, that there can be no void, that things seek their own place, and the like'.

Another mode of reasoning, very widely applied in these attempts, was the doctrine of contrarieties, in which it was assumed, that adjectives or substantives which are in common language, or in some abstract mode of conception, opposed to each other, must point at some fundamental antithesis in nature, which it is important to study. Thus Aristotle3 says, that the Pythagoreans, from the contrasts which number suggests, collected ten principles,Limited and Unlimited, Odd and Even, Onę and Many, Right and Left, Male and Female, Rest and Motion, Straight and Curved, Light and Darkness, Good and Evil, Square and Oblong. We shall see hereafter, that Aristotle himself deduced the doctrine of four elements, and other dogmas, by oppositions of the same kind.

* Timæus, p. 80.

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Metaph. 1. 5.

The physical speculator of the present day will learn without surprise, that such a mode of discussion as this, led to no truths of real or permanent value. The whole mass of the Greek philosophy, therefore, shrinks into an almost imperceptible compass, when viewed with reference to the progress of physical knowledge. Still the general character of this system, and its fortunes from the time of its founders to the overthrow of their authority, are not without their instruction, and, it may be hoped, not without their interest. I proceed, therefore, to give some account of these doctrines in their most fully developed and permanently received form, that in which they were presented by Aristotle.

Sect. 2.-The Aristotelian Physical Philosophy.

THE principal physical treatises of Aristotle are, the eight Books of "Physical Lectures," the four Books "Of the Heavens," the two Books "Of Production and Destruction:" for the Book "Of the World" is now universally acknowledged to be spurious; and the "Meteorologics," though full of physical explanations of natural phenomena, does not exhibit the doctrines and reasonings of the school in so general a form; the same may be said of the "Mechanical Problems." The treatises on the various subjects of Natural History, "On Animals," "On the Parts of Animals,” “On Plants," "On Physiognomonics," "On Colours," "On Sound,"

contain an extraordinary accumulation of facts, and manifest a wonderful power of systematising; but are not works which expound principles, and therefore do not require to be here considered.

The Physical Lectures are the work concerning which a well-known anecdote is related by Simplicius, a Greek commentator of the sixth century, as well as by Plutarch. It is said, that Alexander the Great wrote to his former tutor to this effect; "You have not done well in publishing these lectures; for how shall we, your pupils, excel other men, if you make that public to all, which we learnt from you." To this Aristotle is said to have replied;

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My lectures are published and not published; they will be intelligible to those who heard them, and to none beside." This may very easily be a story inscribed and circulated among those who found the work beyond their comprehension; and it cannot be denied, that to make out the meaning and reasoning of every part, would be a task very laborious and difficult, if not impossible. But we may follow the import of a large portion of the work with sufficient clearness to apprehend the character and principles of the reasoning; and this is what I shall endeavour to do.

The author's introductory statement of his view of the nature of philosophy falls in very closely with what has been said, that he takes his facts and generalisations as they are implied in the structure of language. "We must in all cases proceed," he

says,

"from what is known to what is unknown." This will not be denied; but we can hardly follow him in his inference. He adds, He adds, "we must proceed, therefore, from universal to particular. And something of this," he pursues, "may be seen in language; for names signify things in a general and indefinite manner, as circle, and by defining we unfold them into particulars." He illustrates this by saying, “thus children at first call all men father, and all women mother, but afterwards distinguish.”

In accordance with this view, he endeavours to settle several of the great questions concerning the universe, which had been started among subtle and speculative men, by unfolding the meaning of the words and phrases which are applied to the most general notions of things and relations. We have already noticed this method. A few examples will illustrate it further:-Whether there was or was not a void, or place without matter, had already been debated among rival sects of philosophers. The antagonist arguments were briefly these:-There must be a void, because a body cannot move into a space except it is empty, and therefore without a void there could be no motion :—and, on the other hand, there is no void, for the intervals between bodies are filled with air, and air is something. These opinions had even been supported by reference to experiment. On the one hand, Anaxagoras and his school had shown, that air when confined, resisted compression, by squeezing a blown bladder,