In Hesiod's Theogony, v. 40, we read that when the Muses are singing
"the palace of loud-thundering Jove laughs (with delight) at their lily
voice;" and in the Hymn to Ceres we find Proserpine beholding a
Narcissus, from the root of which a hundred heads sprang forth "and the
whole heavens were scented with its fragrance, and the whole earth
laughed and the briny wave of the sea." Theognis writes that Delos, when
Apollo was born, "was filled with the ambrosial odour, and the huge
earth laughed." The poets seemed scarcely to have advanced beyond such a
bold similitude, and we may conclude that while they saw in laughter
something above the powers of the brute creation, they did not consider
that it necessarily expressed the smallest exercise of intellect.

This laughter of pleasure, which cheered the early centuries of the
world, now no longer exists except perhaps in childhood. It belongs to
simpler if not happier natures than our own. If a man were now to say
that his friends laughed on hearing of some good fortune having come to
him, we should suppose that they disbelieved it, or thought there was
something ridiculous in the occurrence. In these less emotional ages, in
which the manifestations of joy and sorrow are more subdued, it is mute,
and has subsided into a smile. It is difficult to say when the change
took place, but our finding smiles mentioned in Homer, though not in
Scripture, might suggest their Greek origin, if they were at first
merely a modification of the early laughter of pleasure, betokening
little more than kindly or joyous emotions. Although not always now
genial, the smile continues to be used for the symbol of pleasure, even
in reference to inanimate Nature, as where Milton writes "Old Ocean
smiled." The smile may have preceded laughter, as the bud comes before
the blossom, but it may, on the other hand, have been a reduction of
something more demonstrative.