Full Idea
At intervals they removed old timbers from the preserved ship and replaced them with sound ones, so the ship became a classic illustration for the philosophers of the disputed question of growth and change, some saying it was the same, others different.
Gist of Idea
Replacing timbers on Theseus' ship was the classic illustration of the problem of growth and change
Source
Plutarch (Life of Theseus [c.85], 23)
Book Reference
Plutarch: 'The Rise and Fall of Athens', ed/tr. Scott-Kilvert,Ian [Penguin 1960], p.29