Eloy d’Amerval    (April Fool's Day - 1508)

In 1508 Eloy d'Amerval, a French choirmaster and composer, published a poem titled Le livre de la deablerie. It consisted of "a dialogue between Satan and Lucifer, in which their nefarious plotting of future evil deeds is interrupted periodically by the author, who among other accounts of earthly and divine virtue, records useful information on contemporary musical practice."

The poem would principally be of interest to historians of music, except that it includes the line, "maquereau infâme de maint homme et de mainte femme, poisson d'avril."

The phrase "poisson d'avril" (April Fish) is the French term for an April Fool, but it is unclear whether d'Amerval's use of the term referred to April 1st specifically. He might have intended the phrase simply to mean a foolish person.