The ship that Theseus originally used to sail to Athens and the one that was docked in the same harbor one-thousand years later, are very similar in many qualitative aspects. First, the two boats are made of exactly the same parts. As the parts were replaced gradually, the boat still remained the legendary boat that Theseus himself sailed on. Secondly, Theseus sailed on them both, because technically, they both are the same boat. Whether one has no original parts, and the other did, they're both still the same. The newer one is just renovated. In conclusion, both boats, the one that Theseus built and the one that had all it's parts replaced, are still qualitatively the same. Just like how if you changed all your hobbies, changed your life style,
