.

admit the astronomical theories of those who went before him, because they had no proof. He would not give in to their notions about the planets wheeling their rounds in whirlpools of ether for he did not see this ether he had no proof of its existence and, besides, even supposing it to exist, it would not have impressed, on the heavenly bodies, such movements as met his observation. He would not submit his judgment to the reigning systems of the day-for, though they had authority to recommend them, they had no proof; and thus it is, that he evinced the strength and the soundness of his philosophy, as much by his decisions upon those doctrines of science which he rejected, as by his demonstration of those doctrines of science which he was the first to propose, and which now stand out to the eye of posterity as the only monuments to the force and superiority of his understanding.

He wanted no other recommendation for any one article of science, than the recommendation of evidence-and, with this recommendation, he opened to it the chamber

of his mind, though authority scowled upon

and taste was disgusted by it, and fashion was ashamed of it, and all the beauteous speculation of former days was cruelly broken up by this new announcement of the better philosophy, and scattered like the fragments of an aërial vision, over which the past generations of the world had been slumbering their profound and their pleasing reverie. But, on the other hand, should the article of science want the recommendation of evidence, he shut against it all the avenues of his understanding-aye, and though all antiquity lent their suffrages to it, and all eloquence had thrown around it the most attractive brilliancy, and all habit had incorporated it with every system of every seminary in Europe, and all fancy had arrayed it in graces of the most tempting solicitation; yet was the steady and inflexible mind of Newton proof against this whole weight of authority and allurement, and, casting his cold and unwelcome look at the specious plausibility, he rebuked it from his presence. The strength of his philosophy lay as much in refusing admittance to that which wanted evidence, as in giving a place and an occu

pancy to that which possessed it. In that march of intellect, which led him onwards through the rich and magnificent field of his discoveries, he pondered every step; and, while he advanced with a firm and assured movement, wherever the light of evidence carried him, he never suffered any glare of imagination or of prejudice to seduce him from his path.

Sure I am, that, in the prosecution of his wonderful career, he found himself on a way beset with temptation upon every side of him. It was not merely that he had the reigning taste and philosophy of the times to contend with; but, he expatiated on a lofty region, where, in all the giddiness of success, he might have met with much to solicit his fancy, and tempt him to some devious speculation. Had he been like the majority of other men, he would have broken free from the fetters of a sober and chastised understanding, and, giving wing to his imagination, had done what philosophers have done after him-been carried away by some meteor of their own forming, or found their amusement in some of their own intellectual

pictures, or palmed some loose and confident plausibilities of their own upon the world. But Newton stood true to his principle, that he would take up with nothing which wanted evidence, and he kept by his demonstrations, and his measurements, and his proofs; and, if it be true that he who ruleth his own spirit is greater than he who taketh a city, there was won, in the solitude of his chamber, many a repeated victory over himself, which should give a brighter lustre to his name than all the conquests he has made on the field of discovery, or than all the splendour of his positive achievements.

I trust you understand, how, though it be one of the maxims of the true philosophy, never to shrink from a doctrine which has evidence on its side, it is another maxim, equally essential to it, never to harbour any doctrine when this evidence is wanting. Take these two maxims along with you, and you will be at no loss to explain the peculiarity, which, more than any other, goes both to characterise and to ennoble the philosophy of Newton. What I allude to is, the precious combination of its strength and of its

modesty. On the one hand, what greater evidence of strength than the fulfilment of that mighty enterprise, by which the heavens have been made its own, and the mechanism of unnumbered worlds has been brought within the grasp of the human understanding? Now, it was by walking in the light of sound and competent evidence, that all this was accomplished. It was by the patient, the strenuous, the unfaltering application of the legitimate instruments of discovery. It was by touching that which was tangible, and looking to that which was visible, and computing that which was measurable, and, in one word, by making a right and a reasonable use of all that proof which the field of nature around us has brought within the limit of sensible observation. This is the arena on which the modern philosophy has won all her victories, and fulfilled all her wondrous achievements, and reared all her proud and enduring monuments, and gathered all her magnificent trophies to that power of intellect with which the hand of a bounteous heaven has so richly gifted the constitution of our species.