Panta rhei Cratylus, Heraclitus Plutarch once told a story about a boat. The Athenians preserved the ship of Theseus that sailed home from Crete (the guy who killed the Minotaur in the Labyrinth and forgot to change the sails with white ones so his father Aegeus threw himself in the sea filled with grief - giving the name of the Aegean sea), and being conscientious custodians of the memory of the mythical hero they replaced each plank as it rotted, and being philosophically inclined as they are - they eventually asked whether the thing in the harbor was still the...