It is supposed that the famous ship sailed by the hero Theseus in a great battle was kept in a harbor as a museum piece, and as the years went by some of the wooden parts began to rot and were replaced by new ones; then, after a century or so, every part had been replaced. The question then is whether the "restored" ship is still the same object as the original.
If it is, then suppose the removed pieces were stored in a warehouse, and after the century, technology was developed that cured their rot and enabled them to be reassembled into a ship. Is this "reconstructed" ship the original ship?
