The difference between the ordinary visual gaze upon the external universe, and the interpreting glance of science, is felt by every cultivated understanding to be immeasurable;--and the contrast is not less between that dull sense of what passes within him, which is forced upon a man by mere practical experience, and the exact consciousness, the discriminative perception, the easy comprehension of his own (and, so far as they are expressed by faithful symbols, of others') states and affections, possessed by the patient analyst of thought and emotion, and careful collector of their laws. The mighty mass of human achievement and human failure, in intellectual research, in moral endeavor, in social economy and government, lapses into order before him, and distributes itself among the provinces of determinate laws. The structure of a child's perplexity, and the fallacies of the most ambitious hypothesis, lie open to him as readily, as to the artisan a flaw in the fabric of his own craft. The creations of art fall before him into their elements; and, dissolving away their constituent _matter_, which is an accident of their age, leave upon his mind their permanent _form_ of beauty, as his guide to a true and noble criticism. The progress and the aberrations of human reason, in its quest of truth, are as clearly appreciated by him, as the passages of happy skill or ignorant roving in some voyage of discovery, when the outlines and relations of the sphere on which it is made become fully known. Discerning distinctly the different kinds of evidence appropriate to different departments of truth, and weighing the scientific value of every idea and method of thought, he is not at the mercy of each superficial impression and obtrusive phase presented to him by the subjects of his contemplation; but he attains a certain rational tact and graduated feeling of certainty in abstract matters of opinion, by which he escapes alike the miseries of undefined doubt, and the passions of unqualified dogmatism. In short, the great idea of Science is applied by him to the complicated workings of the mind of man; interprets the activities of his nature, and gives laws to the administration of his life; and, with wonderful analysis, investigates the properties, and establishes the equation, of their most labyrinthine curves. What a rebuke upon dogmatic sciolists, what a glorious invitation to study, are conveyed in the genial, broad, mental hospitality of the succeeding paragraph! NECESSITY OF LEARNING IN PHILOSOPHY.