In Greek mythology, the hero Theseus, who slew the Minotaur and escaped its maze, returned from Crete to Athens where the Athenians preserved his ship in seaworthy state for more than a thousand years. It was an emblem of courage and a reminder of a national hero that many Greeks considered more legendary than mythological.
The Ship of Theseus was carefully maintained. Parts that rotted away were replaced with exact replicas. And in a ship made almost entirely of wood, crude iron, rope, and sail, everything rots, so eventually everything gets replaced.
Which makes the identity of the ship an interesting question.
