If one would lay his finger upon the secret of Mark Twain's world-wide popularity as a humorist, he would find that secret, primarily, in the universality and humanity of his humour. Mark Twain is a master in the art of broad contrast; incongruity lurks on the surface of his humour; and there is about it a staggering and cyclopean surprise. But these are mere surface qualities, more or less common, though at lower power, to all forms of humour. Nor is his international vogue as a humorist to be attributed to any tricks of style, to any breadth of knowledge, or even to any depth of intellectuality. His hold upon the world is due to qualities, not of the head, but of the heart. I once heard Mr. Clemens say that humour is the key to the hearts of men, for it springs from the heart; and worthy of record is his dictum that there is far more of feeling than of thought in genuine humour. Mark Twain succeeded in “tickling the midriff of the English-speaking races” with a single story; and in time he showed himself to be, not only a man of letters, but also a man of action. His humour has been defined as the sunny break of his serious purpose. Horace Walpole has said that the world is a comedy to the man of thought, a tragedy to the man of feeling. To the great humorist--to Mark Twain--the world was a tragi-comedy. Like Smile Faguet, he seemed at times to feel that grief is the most real and important thing in the world--because it separates us from happiness. He was an exemplar of the highest, truest, sincerest humour, perfectly fulfilling George Meredith's definition: “If you laugh all round him, tumble him, roll him about, deal him a smack, and drop a tear on him, own his likeness to you and yours to your neighbour, spare him as little as you shun, pity him as much as you expose, it is the spirit of Humour that is moving you.” Mark Twain's fun was light-hearted and insouciant, his pathos genuine and profound. “He is, above all,” said that oldest of English journals, 'The Spectator', “the fearless upholder of all that is clean, noble, straightforward, innocent, and manly. . . . If he is a jester, he jests with the mirth of the happiest of the Puritans; he has read much of English knighthood, and translated the best of it into his living pages; and he has assuredly already won a high degree in letters in having added more than any writer since Dickens to the gaiety of the Empire of the English language.” Mark Twain's humour flowed warm from the heart. He enjoyed to the utmost those two inalienable blessings: “laughter and the love of friends.” He woke the laughter of an epoch and numbered a world for his friends. “He is the true consolidator of nations,” said Mr. Augustine Birrell. “His delightful humour is of the kind which dissipates and destroys national prejudices. His truth and his honour, his love of truth and his love of honour, overflow all boundaries. He has made the world better by his presence.”