YSIDIS. Isis was the Egyptian mother goddess and the wife of Osiris. Valerius Maximus tells a brief story about a man who was caught attempting to burn down the temple of Diana at Ephesus so as to gain fame. The citizens decreed that his name should never be known, Factorum dictorumque memorabilium liber VIII.14. Valerius does not give the man's name, but refers the reader to Theopompus, a Greek historian and a contemporary of Philip II and Alexander the Great. It is historically true that Diana's temple at Ephesus was burned down in 356 B.C., on the night Alexander was born. The histories of Theopompus are lost, but the man's name, Herostratus, appears in Solinus's Polyhistoria XL. 2-3, sometimes called Collectanea rerum memorabilium and written soon after A.D. 200.

A man comes forward, claiming that he had burned down the temple of Isis at Athens in order to become famous, HF III.1842-1858. In keeping with ancient and medieval traditions, Chaucer does not mention the man's name. Although the sources say that the temple in question is Diana's temple at Ephesus, Chaucer makes the temple that of Isis at Athens.

Ysidis, the Latin genitive singular of Isis, occurs in final rhyming position, HF III.1844.