E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The sacred vessel made by Theseus (2 syl.) and sent annually from Athens to Delos. This annual festival lasted 30 days, during which no Athenian could be put to death, and as Socrates was condemned during this period his death was deferred till the return of the sacred vessel. The ship had been so often repaired that not a stick of the original vessel remained at the time, yet was it the identical ship. So the body changes from infancy to old age, and though no single particle remains constant, yet the man 6 feet high is identical with his infant body a span long. (Sometimes called Theoris.)