of effective social life; or to render him effectively
sympathetic and leave him subject to the perpetually renewed
pains of sympathy, which, if not counteracted, would seriously
depress his vitality and perhaps destroy the species. Nature,
confronted with this problem, solved it by the invention
of laughter. She endowed man with the instinct to laugh on
contemplation of these minor mishaps of his fellow men; and
so made them occasions of actual benefit to the beholder;
all those things which, apart from laughter, would have
been mildly displeasing and depressing, became objects and
occasions of stimulating beneficial laughter....

For laughter is no exception to the law of primitive sympathy;
but rather illustrates it most clearly and familiarly; the
infectiousness of laughter is notorious and as irresistible
as the infection of fear itself.... The great laugher is the
person of delicately responsive sympathetic reactions; and his
laughter quickly gives place to pity and comforting support,
if our misfortune waxes more severe. Such persons are in
little danger of giving offense by their laughter; for we
detect their ready sympathy and easily laugh with them; they
teach us to be humorous.

H. Merian Allen in his essay "Little Laughs in History" says "The
relaxation of a full laugh clears the brain, restores fit contact
with one's fellows, and so smoothes the way for the solving of knotty
problems."

Linus W. Kline, Ph.D., further elucidates the psychical office of
humor as follows: