#OTD 28 May 1588, the Spanish Armada set sail from Lisbon to invade England

King Philip II of Spain has sent a Latin verse to Queen Elizabeth I demanding the return of Spanish treasure Captain Drake has taken, accept the Pope's religion etc, then the Queen responded in Latin:

Queen Elizabeth I by Unknown English artist, oil on panel, circa 1588 [1]

According to Suetonius, this proverbial phrase originated with emperor Augustus because he was fond of saying: ad Kalendas Graecas soluturos or “They will pay at the Greek Kalends”, meaning never as Greeks don't have Kalends in their calendar.

Emperor Augustus wearing a laurel crown in a painted oval inscribed across bottom: OCTAVIANVS AVGVSTVS by Circle of Peter Paul Rubens, 17th century [1]

Did you know the English word calendar derives from "the kalends", the first day of the Roman month, signifying the start of a new lunar phase and when debts fell due and accounts were reckoned.

Here is how the ancient Romans divided their months:

These debts were inscribed in the kalendaria, effectively an accounting book. Later it became the Calendarium Romanum taken by the early Church for its register list of saints & their feast days. Meaning "list of documents arranged chronologically" from late 15th century. [1]

P.S. Another Roman colloquial expression was: ad Kalendas Graecas or "until the Greek kalends", meaning postponing something forever.