and even accident do frequently inscribe false propositions on the minds, both of young and old. The memory and the understanding are "rasæ tabulæ," for testimony and experience to write upon; though testimony and experience, it is true, are controlled by the natures of physical and of moral existence, by our senses and by our feelings of pain and pleasure: that is, by the very constitution both of the universe and of ourselves. It is indisputable that our senses do not usually write nonsense or falsehood on the memory; but it is equally true that their evidence being mistaken, they do so occasionally, and nothing but patient, persevering analysis, can efface or correct the inscriptions. The difference between visible and tangible magnitude, and to use more homely examples, the delusive perceptions of pain in an amputated limb, and the appearances on the banks of a river while we are sailing, 66 terræque urbesque rece"dunt," are decisive proofs of erroneous conclusions. Indeed it requires much caution to form right opinions; and, as Dr. Moore observes, "if ideas were innate, it "would save much trouble to many worthy persons." Leibnitz, after truly respresenting Locke's doctrine as an exemplification of the ancient maxim, "Nihil est in "intellectu quod non priùs fuerat in sensu," adds, "nisi K "intellectus ipse;" and Mr. Dugald Stewart warmly praises the acuteness of this remark. But how can any man think highly of an axiom which has absurdity in its very expression? Only strike out the middle clause, and see what can be made of "Nihil est in intellectu nisi "intellectus ipse." Why, the question itself in discussion is, "what are the laws of the intellect, and how do "they originate?" In replying to this inquiry, we must, at present, mention instinct as well as perception, though, since the principle of association (that great sensitive and intellectual law!) has been carefully traced, the theory of instinct is daily becoming less and less necessary to account for the phenomena. Here lie (and but little below the surface) the seeds of a rich harvest for the sickle of future metaphysicians. Sensation and association will probably be found to account for nearly all the appearances. Thus in Ethics, the existence of a moral sense cannot be doubted; but its instinctive, innate origin is, I suppose, given up by most philosophers, and habit, unavoidable habit, is admitted to be its source. A stumble at the threshold, not unlike Leibnitz' false-step, occurs in the elementary dictum of some eminent modern materialists: "Movent sed non promo "vent." Two great teachers in this school have defined an idea to be "a motion in the brain perceived." Now, did any man ever perceive a motion in his brain? There may be, and there probably is a motion there, and it may be followed by perception; but who has ever perceived the motion, or detected the connection? Anatomists and physiologists may do their utmost, but there will always remain an undiscovered something between the bodily organ and the percipient power. In subjects of this kind (and indeed in all subjects) it is best to learn, as it were, the alphabet of the doctrine. Many a time something may be found in the first chapter of a book, rendering it needless to read on; and when it happens otherwise, still the benefit of examining first principles is great. The ascent from the bottom of the hill may be fatiguing; but, when the summit is attained, what a prospect! What a distance between a minute examination of the mere letters composing a word, and the sublime theory that may be disclosed in its import! You must sometimes have been surprised by the length of your journeys. TO FRANCIS HORNER, ESQ. Fredley Farm, 18th June, 1805. I AM not surprised that you have reflected as you say, again and again," on the subject of our singular conversation, although you still smile at our having fallen upon such a topic, in our long walk among the woods of NORBURY. No subject can well be more important, and none is more perplexing-it is a sea almost without a shore. In Turgot's article, "Existence," he hardly exaggerates, though he says, "Les degrés de probabilité "dont une juste estime et une exacte mesure seroient le "comble de la sagacité et de la prudence." Hear Lucretius too: "Nam nihil egregiùs quàm res secernere apertas And Cicero: "Benè qui conjiciet vatem hunc perhibebo I agree with you, however, that a common opinion intimated by Gibbon, in the following passage, is not true. 66 "I desisted from the pursuit of mathematics, before my mind was hardened by the habit of rigid demon"stration, so destructive of the finer feelings of moral "evidence; which determine the actions and opinions of 66 our lives." Are we not more benefited by the habits of close attention formed in the study of mathematics, than injured by the hardening process which he dreaded? Surely the necessity of walking all our lives in the twilight of probable evidence, corrects the searing influence of our seeing occasionally by the blaze of a noonday sun. It is remarkable, that the rules of probability have always been spoken of as important desiderata, and that several of the greatest authors have declared their intention to treat of them at length; but, somehow or other, they have always put off the task to another day. Leibnitz even tells Thomas Burnet in a letter, "Si Dieu me "donne encore de la vie et de la santé, j'en ferai ma principale affaire." 66 It has often struck me, that this never-failing post ponement of the arduous undertaking cannot have arisen |