To Laugh, If But For An Instant Only, Has Never Been Granted To Man
Before The Fortieth Day From His Birth, And Then It Is Looked Upon
As A Miracle Of Precocity.
To laugh, if but for an instant only, has never been granted to man
before the fortieth day from his birth, and then it is looked upon
as a miracle of precocity.
-- Pliny the Elder (23-79 AD)
-- Natural History, Book vii, Sect. 2