I have expected to kill myself for the last three months, finishing an addition to my work on the origin and changes of the French civil law. It will take only three hours to read it; but, I assure you, it has been such a labor to me, that my hair has turned white under it all. Finally it touches nadir: It [his work] has almost cost me my life; I must rest; I can work no more. My candles are all burned out; I have set off all my cartridges. When Montesquieu died, only Diderot, among Parisian men of letters, followed him to his tomb. Belonging to an entirely different world, literary, social, political, from that in which Montesquieu flourished--more than one full century, and that a French century, had intervened--was a man kindred in genius with him, to whom, for the double reason that his intellectual rank deserves it, and that the subject of his principal work is one to command especially the interest of Americans, we feel compelled to devote serious, though it must be hastening, attention. We refer to Alexis de TOCQUEVILLE, the author of that famous book, "Democracy in America." We can most conveniently discharge our duty by letting their likeness in intellectual character and achievement bridge for us the chasm of time between the two men, and thus considering the later in conjunction here with the earlier author. "Democracy in America" is a most remarkable book to have been, as in fact it was, the production of a young man of thirty. It was the fruit of a tour in the United States undertaken by the writer ostensibly to visit in an official capacity the prisons of the new nation that France had helped create, in a kind of counterpoise to England, on this side of the Atlantic. The inquisitive young French inspector inspected much more than the prison system of the lusty infant republic. He observed and studied American institutions and manners at large, in order to lay a base line for the boldest speculative triangulation into the probable political future of the world.