day, or a fit of indigestion, would deprive an inventor of his theory all at once; and as one of them said, “after dinner, all that I have written in the morning appears to me dark, incongruous, nonsensical.”  At such moments we should find this man of genius in no pleasant mood.  The true cause of this nervous state cannot, nay, must not, be confided to the world:  the honour of his darling theory will always be dearer to his pride than the confession of even slight doubts which may shake its truth.  It is a curious fact which we have but recently discovered, that ROUSSEAU was disturbed by a terror he experienced, and which we well know was not unfounded, that his theories of education were false and absurd.  He could not endure to read a page in his own “Emile"[A] without disgust after the work had been published!  He acknowledged that there were more suffrages against his notions than for them.  “I am not displeased,” says he, “with myself on the style and eloquence, but I still dread that my writings are good for nothing at the bottom, and that all my theories are full of extravagance.” [Je crains toujours que je peche par le fond, et que tous mes systemes ne sont que 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!