.....[E]ver will a coward show no mercy, and
always a good man will do ever to another man as he would be done to himself.
..........— Sir Thomas Mallory (c. 1408-1471), author.
Le Morte d’Authur (1485). Quoted in William Henry Schofield,
Chivalry in English Literature: Chaucer, Malory, Spenser, and Shakespeare (Cambridge, MA: Harvard University, 1912), page 96.

Detail from
The Last Sleep of Arthur by Edward Burne-Jones, who often found inspiration in
Le Morte d'Arthur.
(Public domain image downloaded from Wikipedia — click to enlarge.)