The preservation and posthumous publication of private correspondence has supplied modern society with one of its daintiest literary luxuries. The art of letter-writing is, of course, no recent invention; it reached a high level of excellence, like almost every other branch of refined expression in prose or verse, in the older world of Rome. Nevertheless, the exceeding rarity of the specimens that have come down to us from those times is an important element of their value; while in our own day the letters of eminent persons fill many book-shelves in every decent library, and their quantity increases out of all proportion to their quality. It may be said, generally, of fine letter-writing that it is a distinctive product of a high civilisation, denoting the existence of a cultured and leisurely class, implying the conditions of secure intercourse, confidence, sociability, many common interests, and that peculiar delight in the stimulating interchange of ideas and feelings which is one characteristic of modern life. The language of a country must have thrown off its archaic stiffness, must have acquired suppleness and variety; the writer's instrument must be a style that combines familiarity with distinction, correctness of thought with easy diction. It is from the lack of these conditions that the Asiatic world has given us no such letters; the material as well as the intellectual environment has been wanting. For similar reasons the middle ages of Europe produced us none of the kind with which we are now dealing; the sixteenth and the seventeenth centuries have left us very few samples of them; and since in this article we propose to treat only of English letter-writers, we may affirm that the art did not flourish in England until the eighteenth century, when according to certain authorities it rose to something like perfection. It is a notable observation of Hume's that Swift is the first Englishman who wrote polite prose; and Swift is one of the earliest, as he is still one of the pleasantest, writers of private correspondence that has taken a permanent place in our literature.