Three books, still living, are associated with the name of Montesquieu--"The Persian Letters," "The Greatness and the Decline of the Romans," and "The Spirit of Laws." "The Persian Letters" are a series of epistles purporting to be written by a Persian sojourning in Paris and observing the manners and morals of the people around him. The idea is ingenious; though the ingenuity, we suppose, was not original with Montesquieu. Such letters afford the writer of them an admirable advantage for telling satire on contemporary follies. This production of Montesquieu became the suggestive example to Goldsmith for his "Citizen of the World; or, Letters of a Chinese Philosopher." We shall have here no room for illustrative citations from Montesquieu's "Persian Letters." The second work, that on the "Greatness and the Decline of the Romans," is less a history than a series of essays on the history of Rome. It is brilliant, striking, suggestive. It aims to be philosophical rather than historical. It deals in bold generalizations. The spirit of it is, perhaps, too constantly and too profoundly hostile to the Romans. Something of the ancient Gallic enmity--as if a derivation from that last and noblest of the Gauls, Vercingetorix--seems to animate the Frenchman in discussing the character and the career of the great conquering nation of antiquity. The critical element is the element chiefly wanting to make Montesquieu's work equal to the demands of modern historical scholarship. Montesquieu was, however, a full worthy forerunner of the philosophical historians of to-day. We give a single extract in illustration--an extract condensed from the chapter in which the author analyzes and expounds the foreign policy of the Romans. The generalizations are bold and brilliant,--too bold, probably, for strict critical truth. (We use, for our extract, the recent translation by Mr. Jehu Baker, who enriches his volume with original notes of no little interest and value.) Montesquieu: This body [the Roman Senate] erected itself into a tribunal for the judgment of all peoples, and at the end of every war it decided upon the punishment and the recompenses which it conceived each to be entitled to. It took away parts of the lands of the conquered states, in order to bestow them upon the allies of Rome, thus accomplishing two objects at once--attaching to Rome those kings of whom she had little to fear and much to hope, and weakening those of whom she had little to hope and all to fear. Allies were employed to make war upon an enemy, but the destroyers were at once destroyed in their turn. Philip was beaten with the half of the AEtolians, who were immediately afterward annihilated for having joined themselves to Antiochus. Antiochus was beaten with the help of the Rhodians, who, after having received signal rewards, were humiliated forever, under the pretext that they had requested that peace might be made with Perseus.