It is recorded of this almost superhuman Genius, whose powers and attainments at once make us proud of our common nature, and humble us with our disparity, that, in acquiring the Elements of Geometry, he was able, in a very large proportion of cases, to pass immediately from Theorem to Theorem, by reading the mere enunciation of each, perceiving, as it were intuitively, that latent evidence, which others are obliged slowly to trace through a long series of Propositions. When the same Theorem was enunciated, or the same simple phenomenon observed, the successions of thought, in his mind, were thus obviously different from the successions of thought in other minds; but it is easy to conceive the original susceptibilities of all minds such, as exactly to have corresponded with those of the mind of Newton. And if the minds of all men, from the creation of the world, had been similar to the mind of Newton, is it possible to conceive, that the state of any science would have been, at this moment, what it now is, or in any respect similar to what it now is, though the laws which regulate the physical changes in the material universe, had continued unaltered, and no change occurred, but in the simple original susceptibilities of the mind itself? The laws of the observing and comparing mind, then, it must be admitted, have modified, and must always continue to modify, every science, as truly as the laws of that particular department of nature of which the phenomena are observed and compared. But, it may be said, we are Chemists, we are Astronomers, without studying the philosophy of mind. And true it certainly is, that there are excellent Astronomers, and excellent Chemists, who have never paid any particular attention to intellectual philosophy. The general principles of philosophizing, which a more accurate intellectual philosophy had introduced, have become familiar to them, without study. But those general principles are not less the effect of that improved philosophy of mind, any more than astronomy and chemistry themselves have now a less title to be considered as sciences,--because, from the general diffusion of knowledge in society, those who have never professedly studied either science, are acquainted with many of their most striking truths. It is gradually, and almost insensibly, that truths diffuse themselves--at first admired and adopted by a few, who are able to compare the present with the past, and who gladly own them, as additions to former knowledge,--from them communicated to a wider circle, who receive them, without discussion, as if familiar and long known; and at length, in this widening progress, becoming so nearly universal, as almost to seem effects of a natural instinctive law of human thought:--like the light, which we readily ascribe to the sun, as it first flows directly from him, and forces his image on our sight; but which, when reflected from object to object, soon ceases to remind us of its origin, and seems