Theseus - Ship of Theseus

Ship of Theseus

According to Plutarch's Life of Theseus, the ship Theseus used on his return from Crete to Athens was kept in the Athenian harbor as a memorial for several centuries.

The ship wherein Theseus and the youth of Athens returned had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their place...

The ship had to be maintained in a seaworthy state, for, in return for Theseus's successful mission, the Athenians had pledged to honour Apollo every year henceforth. Thus, the Athenians sent a religious mission to the island of Delos (one of Apollo's most sacred sanctuaries) on the Athenian state galley — the ship itself — to pay their fealty to the god. To preserve the purity of the occasion, no executions were permitted between the time when the religious ceremony began to when the ship returned from Delos, which took several weeks.

To preserve the ship, any wood that wore out or rotted was replaced; it was, thus, unclear to philosophers how much of the original ship actually remained, giving rise to the philosophical question whether it should be considered "the same" ship or not. Such philosophical questions about the nature of identity are sometimes referred to as the Ship of Theseus Paradox.

Regardless of these issues of the originality of the ship's structure, for Athenians the preserved ship kept fresh their understanding that Theseus had been an actual, historic figure — which none then doubted — and gave them a tangible connection to their divine providence.