American, a Scotchman, an Irishman, a Frenchman, carries with it a
distinctive racial flavour and individuality of approach. Indeed, it is
open to question whether most humour is not essentially local in its
nature, requiring some specialized knowledge of some particular
locality. It would be quite impossible for an Italian on his native
heath to understand that great political satirist, "Mr. Dooley," on the
Negro Problem, for example. After reading George Ade's Fables in Slang,
Mr. Andrew Lang was driven to the desperate conclusion that humour
varies with the parallels of latitude, a joke in Chicago being a riddle
in London.

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