There are many superstitions concerning sneezing. It is said
that the custom of blessing one who sneezes originated in Italy
in the time of Pope Gregory the Great (ca. 540–604) during a
pestilence that proved fatal to those who sneezed. A still older
date is given to this custom by some writers, who traced the idea
to the biblical Adam and to his descendent Jacob, who supposedly
begged that its fatal effects might be removed. On his request
being granted, the people gratefully instituted the custom
of saluting the sneezer.
In some diseases, sneezing was a bad omen, while in others
it was a good omen. Sneezing to the right was lucky, to the left,
unlucky; from noon to midnight good, from night to noon,
bad. St. Augustine (d. 430) stated that the ancients would return
to bed if they sneezed while putting on a shoe.