||We know of 8 events of note in literature and the arts that occurred on May 21:
- According to Hellenic tradition, the Greek philosopher Plato was born on this day in 427 BCE. Plato was not his actual birth name. Socrates' greatest student was a portly man, and Plato is a form of the Greek sobriquet something like the English nickname Tubby. Aristotle said, "I hold Plato dear, but I hold truth dearer."
- On this day in 1864 Belgian missionary priest Father Damien, 24, was ordained on the Island of Hawaii. Born Joseph de Veuster, the Picpus Father began a work among the lepers on the island of Molokai in 1873. Contracting the disease in 1884, Father Damien succumbed to it five years later.
- On this day in 1881, Clara Barton founded the American Red Cross.
- On this day in 1892, the opera I Pagliacci by Ruggiero Leoncavallo was performed for the first time in Milan, Italy. It fast became one of the most popular operas of all time, with "Vesti la giubba" one of the most demanded arias in the repertoire.
- On this day in 1916, Britain began Summer Time (Daylight Savings Time).
- On this day in 1935, reformer Jane Addams, a founder of the ACLU, died at 65.
- On this day in 1959, the musical Gypsy opened on Broadway.
- Two American pop-novelists were born on this day: Harold Robbins in 1916, and priest turned writer Robert Creeley in 1926.