Montesquieu's genius was essentially moral and political; it was on man himself, not the material world with which he was surrounded, that his thoughts were fixed. This strong bent soon appeared in his writings. He next read at the academy at Bourdeaux, a "Life of the Duke of Berwick," and an "Essay on the Policy of the Romans in Religion," which was the basis of the immortal work which he afterwards composed on the rise and fall of that extraordinary people. These desultory essays gave no indication of the first considerable work which he published, which was the famous _Lettres Persanes_. They appeared in 1721, when he was thirty-two years of age. Their success was immediate and prodigious; a certain indication in matters of thought, that they were not destined to durable fame. They fell in with the ideas and passions of the time; they were not before it; thence their early popularity and ultimate oblivion. The work was published anonymously; for the keen but delicate satire on French manners and vices which it contained, might have endangered the author, and as it was he had no small difficulty, when it was known he was the writer, in escaping from its effects. It consists in a series of letters from an imaginary character, Usbeck, a Persian traveller, detailing the vices, manners, and customs of the French metropolis. The ingenuity, sarcasm, and truth, which that once celebrated production contains, must not make us shut our eyes to its glaring defects; the vices of the age, as they mainly contributed to its early popularity, have been the chief cause of its subsequent decline. It contains many passages improperly warm and voluptuous, and some which, under the mask of attacks on the Jesuits, had the appearance, at least, of being levelled at religion itself. No work, at that period, could attract attention in France which was not disfigured by these blemishes. Even the great mind of Montesquieu, in its first essay before the public, did not escape the contagion of the age.