des extravagances._] HARTLEY with his "Vibrations and Vibrationeles," LEIBNITZ with his "Monads," CUDWORTH with his "Plastic Natures," MALEBRANCHE with his paradoxical doctrine of "Seeing all things in God," and BURNET with his heretical "Theory of the Earth," must unquestionably at times have betrayed an irritability which those about them may have attributed to temper, rather than to genius. [Footnote A: In a letter by Hume to Blair, written in 1766, apparently first published in the _Literary Gazette_, Nov. 17, 1821.] Is our man of genius--not the victim of fancy, but the slave of truth--a learned author? Of the living waters of human knowledge it cannot be said that "If a man drink thereof, he shall never thirst again." What volumes remain to open! what manuscript but makes his heart palpitate! There is no term in researches which new facts may not alter, and a single date may not dissolve. Truth! thou fascinating, but severe mistress, thy adorers are often broken down in thy servitude, performing a thousand unregarded task-works! Now winding thee through thy labyrinth with a single thread, often unravelling--now feeling their way in darkness, doubtful if it be thyself they are touching. How much of the real labour of genius and erudition must remain concealed from the world, and never be reached by their penetration! MONTESQUIEU has described this feeling after its agony: "I thought I should have killed myself these three months to finish a _morceau_ (for his great work), which I wished to insert, on the origin and revolutions of the civil laws in France. You will read it in three hours; but I do assure you that it cost me so much labour that it has whitened my hair." Mr. Hallam, stopping to admire the genius of GIBBON, exclaims, "In this, as in many other places, the masterly boldness and precision of his outline, which astonish those who have trodden parts of the same field, is apt to escape an uninformed reader." Thrice has my learned friend, SHARON TURNER, recomposed, with renewed researches, the history of our ancestors, of which Milton and Hume had despaired--thrice, amidst the self-contests of ill-health and professional duties!