distinguished into the old, the middle, and the new Academy. The old Academy consisted of those followers of Plato who taught his doctrine without corruption. It was the doctrine of the new Academy (founded by Carneades) that the senses, the understanding, and the imagination, frequently deceive us, and therefore cannot be infallible judges of truth; but that, from the impressions which we perceive to be produced on the mind by means of the senses, we infer appearances of truth, or probabilities: these impressions Carneades called phantasies or images. He maintained that they do not always correspond to the real nature of things; and that there is no infallible method of determining when they are true or false. Nevertheless, with respect to the conduct of life and the pursuit of happiness, Carneades held, that probable appearances are a sufficient guide, because it is unreasonable not to allow some degree of credit to those witnesses who commonly give a true report.

Of probabilities Carneades made the following scale: -The lowest degree was, where the mind, in the casual occurrence of any single image, perceived in it nothing contrary to nature or truth. The second was, when the circumstances by which that image was accompanied afforded no appearance of inconsistency or incongruity which might lead us to suspect the truth of the sensation: as, for instance, if I think I see a horse, the circumstance of his appearing at the same time to be grazing in a meadow is an additional corroboration of the truth of the sensation; but if I think I see a horse upon the top of a house, the circumstances which accompany this idea of the horse, ought to go some way to convince me I am mad, or dreaming. The last point in the scale of probabilities I can really hardly distinguish from the second; it seems only a longer and more serious pause, a more cautious and minute examination of the evidence of the senses; - and thus much of the

philosophy of the new Academy (stripped of the magisterial and ostentatious garb in which all the Grecian schools tricked out their theories) seems to be good plain sense. All knowledge founded upon the evidence of the senses is, and can be, strictly speaking, nothing more than probable evidence. The mathematics alone afford us certain evidence.

The shade of difference between the middle Academy and the new are so slight, and the sketch I am attempting to give must necessarily be so very summary, that I shall pass over this first ramification of the Platonic school to the philosophy of Aristotle; humbly imploring the forgiveness of those disciples of Arcesilaus, and favourers of the middle Academy, who may happen to be present this day at the Institution.

Whoever is fond of the biographical art, as a repository of the actions and the fortunes of great men, may enjoy an agreeable specimen of its certainty in the life of Aristotle. Some writers say he was a Jew; others, that he got all his information from a Jew, that he kept an apothecary's shop, and was an atheist; others say, on the contrary, that he did not keep an apothecary's shop, and that he was a Trinitarian. Some say he respected the religion of his country; others that he offered sacrifices to his wife, and made hymns in favour of his father-in-law. Some are of opinion he was poisoned by the priests; others are clear that he died of vexation, because he could not discover the causes of the ebb and flow in the Euripus. We now care or know so little about Aristotle, that Mr. Fielding, in one of his novels, says, "Aristotle is not such a fool as แ many people believe, who never read a syllable of his "works."

Before the Reformation, his morals used to be read to the people in some of the churches of Germany, instead of the Scriptures; his philosophy had an exclusive monopoly granted to it by the parliament of Paris, who

forbad the use of any other in France; and the President De Thou informs us, that Paul de Foix, one of the most learned and elegant men of his time, in passing through Ferrara, refused to see the famous Patricius, or to meet him at any third house, because he disbelieved in some of the doctrines of Aristotle. Certainly the two human beings who have had the greatest influence upon the understandings of mankind have been Aristotle and Lord Bacon. To Lord Bacon we are indebted for an almost daily extension of our knowledge of the laws of nature in the outward world; and the same modest and cautious spirit of inquiry extended to Moral Philosophy, will probably at last give us clear, intelligible ideas of our spiritual nature. Every succeeding year is an additional confirmation to us that we are travelling in the true path of knowledge; and as it brings in fresh tributes of science for the increase of human happiness, it extorts from us fresh tributes of praise to the guide and father of true philosophy. To the understanding of Aristotle, equally vast, perhaps, and equally original, we are indebted for fifteen hundred years of quibbling and ignorance; in which the earth fell under the tyranny of words, and philosophers quarrelled with one another, like drunken men in dark rooms who hate peace without knowing why they fight, or seeing how to take aim. Professors were multiplied without the world becoming wiser; and volumes of Aristotelian philosophy were written which, if piled one upon another, would have equalled the Tower of Babel in height, and far exceeded it in confusion. Such are the obligations we owe to the mighty Stagirite; for that he was of very mighty understanding, the broad circumference and the deep root of his philosophy most lamentably evince. His treatises on Government, on Rhetoric, on Poetry, are still highly valued. I have been speaking of him as a natural philosopher, as a metaphysician, and as a logician. I would refer those

who are great sticklers for Aristotle's various treatises on morals to Grotius' critique on them in his treatise on Peace and War, and to Barbeyrac's preface to Puffendorf. Of his experiments Lord Bacon says, that, of all the ancient philosophers, Aristotle was the greatest enemy to experimental philosophy; for he first of all laid down a theory in his own mind, and then distorted his experiments to support it. In his treatise on Government there are some very enormous and atrocious doctrines.

Aristotle held, that all sensible objects were made up of two principles, both of which he calls equally substances,―the matter, and the specific essence. He was not obliged to hold, like Plato, that those principles existed prior in order of time to the objects which they afterwards composed. They were prior, he said, in nature, but not in time (according to a distinction which was of use to him upon many other occasions). He distinguished also between actual and potential existence: by the first, understanding what is commonly meant by existence, or reality; by the second, the bare possibility of existence. Neither the material essence of body could, according to him, exist actually without being determined by some specific essence to some particular class of being, nor any specific essence without being embodied in some portion of matter. Each of these two principles, however, could exist potentially in a separate state. That matter existed potentially which, being endowed with a particular form, could be brought into actual existence; and that form existed potentially which, by being embodied in a particular portion of matter, could in the same manner be called forth into the class of complete realities. What difference there is between the potential existence of Aristotle, and the separate essences of Plato, and what foundation there is in reality either for the one or the other, I confess myself wholly at a loss to comprehend.

Virtue, according to this philosopher, consists in the habit of mediocrity according to right reason. Every particular virtue, according to him, lies in a medium between two opposite vices; of which the one offends from being too much, the other from being too little affected by a particular species of objects. Thus, the virtue of fortitude lies in the middle between the opposite extremes of cowardice and rashness; of which the one offends from being too much, the other too little affected by the objects of fear. And magnanimity, in the same manner, is a sort of medium estimation of our own dignity, equally removed from the extremes of arrogance and pusillanimity.

Aristotle, when he made virtue to consist in practical habits, had it probably in view to oppose the doctrine of Plato, who seems to have been of opinion that just sentiments, and reasonable judgments, concerning what was fit to be done or avoided, were alone sufficient to constitute the most perfect virtue. Virtue, according to Plato, might be considered as a sort of science; and no man, he thought, could see clearly what was right and wrong, and not act accordingly. Aristotle, on the contrary, was of opinion, that no conviction of the understanding could get the better of inveterate habits; and that good morals arose not from knowledge, but from action.

Next comes the Stoic sect, whose founder was Zeno. Zeno was born at Cyprus, and was the son of a merchant, who, having frequent occasion in his mercantile capacity to visit Athens, bought for his son several of the writings of the most eminent Socratic philosophers. These he read with great avidity, and from their

According to Zeno, the founder of the Stoical doctrine, every animal was by nature recommended to its own care; and was endowed with the principle of self-love, that it might endeavour to preserve, not only its existence, but all the different parts of its nature, in the best and most perfect state of which they were capable.-Adam Smith's Theory of Moral Sentiments, vol. ii. part vii. sect. 2.