The self-conscious nineteenth century is full of comments on this topic, as on all others, but two or three representative ones will suffice as examples.
It is not really the great Greek satirist but his modern interpreter who utters this explanatory sentiment:
"Now, earnestness seems never earnest more
Than when it dons for garb—indifference;
So, there's much laughing: but, compensative,
When frowning follows laughter, then indeed
Scout innuendo, sarcasm, irony!"[1]
Finally, turning to the encyclopedia for a modern official pronouncement, we find humor again cited as a sine qua non.[2]
"Satire in its literary aspect may be defined as the expression
in adequate terms of the sense of amusement or disgust excited
by the ridiculous or unseemly, provided that humor is a distinctly
recognisable element, and that the utterance is invested
with literary form. Without humor, satire is invective; without
literary form, it is mere clownish jesting. * * * This
feeling of disgust or contempt may be diverted from the
failings of man individual to the feebleness and imperfection
of man universal, and the composition may still be a satire;
but if the element of scorn or sarcasm were entirely eliminated
it would become a sermon."
The matter of ingredients is more easily disposed of,
however, than that of causation. It is obviously easier
to scrutinize a finished product and see what it is made
of than to go back to its origin and discover why it was
made. For the latter process leads us to the domain of
motives, that shadowy realm where the real is often made
to hide behind the assumed or at least the instinctive
