The infant of literature "wails" and wails feebly, with the invariability
of a thing unproved and taken for granted. Nothing, nevertheless, could
be more unlike a wail than the most distinctive cry whereon the child of
man catches his first breath. It is a hasty, huddled outcry, sharp and
brief, rather deep than shrill in tone. With all deference to old
moralities, man does not weep at beginning this world; he simply lifts up
his new voice much as do the birds in the Zoological Gardens, and with
much the same tone as some of the duck kind there. He does not weep for
some months to come. His outcry soon becomes the human cry that is
better known than loved, but tears belong to later infancy. And if the
infant of days neither wails nor weeps, the infant of months is still too
young to be gay. A child's mirth, when at last it begins, is his first
secret; you understand little of it. The first smile (for the convulsive
movement in sleep that is popularly adorned by that name is not a smile)
is an uncertain sketch of a smile, unpractised but unmistakable. It is
accompanied by a single sound--a sound that would be a monosyllable if it
were articulate--which is the utterance, though hardly the communication,
of a private jollity. That and that alone is the real beginning of human
laughter.

From the end of the first fortnight in life, when it appears for the
first time, and as it were flickeringly, the child's smile begins to grow
definite and, gradually, more frequent. By very slow degrees the secrecy
passes away, and the dryness becomes more genial. The child now smiles
more openly, but he is still very unlike the laughing creature of so much
prose and verse. His laughter takes a long time to form. The
monosyllable grows louder, and then comes to be repeated with little
catches of the breath. The humour upon which he learns to laugh is that
of something which approaches him quickly and then withdraws. This is
the first intelligible jest of jesting man.