grave attire. It is only by abstracting our mind from the inquiry, and
throwing it into lighter considerations, that we can at all retain the
illusion. A clever sally appears brilliant when it breaks suddenly upon
the mental vision, but when it is brought forward for close examination
it loses half its lustre, and seems to melt into unsubstantial air.
Humour may be compared to a delicate scent, which we only perceive at
the first moment, or to evanescent beauty--

"For every touch that wooed its stay
Has brushed its brightest hues away."

This last simile is especially in point here, and the quotations in this
book will scarcely be found humorous, so long as they are regarded as
mere illustrations of the nature of humour.

We need not--taking these matters into consideration--feel much
surprised that some people say the ludicrous cannot be defined; as for
instance, Buckingham,

"True wit is everlasting like the sun,
Describing all men, but described by none;"

and Addison:--"It is much easier to decide what is not humorous than
what is, and very difficult to define it otherwise than Cowley has done,
by negatives"--the only meaning of which is that the subject is
surrounded with rather more than the usual difficulties attending moral
and psychological researches. Similar obstacles would be encountered in
answering the question, "What is poetry?" or "What is love?" We can only
say that even here there must be some surroundings by which we can
increase our knowledge.