"Good sense is at once the basis of and the limit to all humor. He who lacks a fine perception of 'the difference between what things are and what they ought to be,' as the always-to-be-quoted Hazlitt expressed it, can never write humor. All the way through we shall find that mirth is a matter of relationships, of shift, of rigidity trying to be flexible, of something shocked into something else.
"Let us think of a circle on which four points have been marked:
"Beginning with a serious idea, we may swiftly step from point to point until we return to the serious, with only slight variations from the original conception. Take the perennial comedy-theme of the impish collar, and visualize the scenes:
"1. A man starts to button his collar. Nothing is less comical, as long as the operation proceeds normally.
"2. But the button is too large and his efforts begin to exasperate him, with the result that his expression and movements become incongruous. We see, and laugh—though he does not.
"3. He begins to hop around in a mad attempt to button the unbuttonable, and soon rips off the collar, addressing it in unparliamentary language. He is ludicrous, ridiculous, absurd.
"4. In his rage he violently kicks a pet dog that comes wagging up to him. Our laughter subsides, for the fellow is more contemptible than amusing—a deeper feeling has been born in us.
"5. The little dog limps off with a broken leg—we are no longer amused, we are indignant. What is more, not only have we gotten back to the serious, but there is no amusement left in any of the previous scenes.
"Still applying the test of the extent of the variation from the normal as shown in the effects, we conclude that serious consequences kill humor. The mere idea of such consequences, when we know that in the circumstances they are really impossible, may convulse us with merriment, as when we see a comedian jab a long finger into the mouth of his teammate and the latter chews it savagely. In real life this might sicken us with disgust—I say 'might,' because we can easily conceive of such a situation's exciting laughter if the victim were well deserving of the punishment. It is human for us to laugh when the biter is bit; indeed, variations on this theme are endless in humorous writing.