laugh, tho it remains but an attempt, an effort, an aspiration
after something which he seems to have lost but wishes to
recover. Either, that is, he remains grave when others laugh,
or he laughs, as Horace says, "with alien jaws," by constraint
rather than because he cannot help it. He has a confused idea
that it is expected of him. Such laughter is apparently the
outcome of an uneasy sense of duty, a dismal travesty of the
real thing....

Certainly humour is a singularly elusive thing, and I doubt
if anyone alive can explain it; but its elusiveness gives it
something of its charm; and, moreover, the illustrations which
are necessary to an inquiry into its nature, its scope and
meaning, are apt to be amusing without being irrelevant.

Humour has often been roughly described as a sense of the
incongruous. More satisfying, however, is the following, which
has been ascribed to Dean Inge: It is a sense of incongruous
emotions. As soon as we think of the emotions being stirred
we see that the strange difference between humourous and
unhumourous people is not an intellectual matter, but follows
the general law of emotional susceptibility, viz., that it is
independent of the reason and varies within wide limits
with each individual, and obviously with each nationality.
Moreover, it appears that, as it is compounded of two
emotions, one man may feel one of the emotions but be dull
to the other, according to his temperament. It is a matter of
sensitiveness, and in sensitiveness no two of us are alike.

Crudely judged, then, humour may be described as a blessing of