Is there an idiom or saying for something that has been entirely replaced but only one part at a time, so you can technically claim that it's still the same thing? Kind of like piecemeal upgrades but that's not quite what I'm thinking of.

  • This is easier with say 'It's a common belief that the human body completely renews itself every seven years ...' {New Scientist}. But with the famous sweeping brush ("I've had it for 37 years! It's had five new heads and three new stales.") 'renew' doesn't really work, even though it can be used non-reflexively. Commented Apr 3, 2018 at 10:37
  • I think the 'broom gag' may well be what I'm thinking of actually... I wonder if anyone knows a more concise expression of the joke.
    – Earl Sven
    Commented Apr 3, 2018 at 10:39
  • 1
    In the US, It would more commonly be 'grandad's hammer - with three new handles and a couple of new heads". I think this might be a dup.
    – Phil Sweet
    Commented Apr 3, 2018 at 10:39

1 Answer 1


The Ship of Theseus is

a thought experiment that raises the question of whether an object that has had all of its components replaced remains fundamentally the same object.

To paraphrase Wikipedia, ancient Greek philosophers had discussed this paradox but it was Plutarch who gave it this name.

The USS Constellation, an Age of Sail sloop of war in Baltimore harbor, is a literal Ship of Theseus, having been rebuilt in 1854 using some wood from a previous ship also called the Constellation, and much of this wood had to be replaced during a 1990s conservation effort.

According to This EL&U question, Heraclitus tried to resolve the paradox by saying each time you cross a stream, it's the same stream but different water.

Finally, here's a Skeptics SE answer that confirms the atoms in our bodies are continually being replaced. So we're all ships of Theseus.

  • This is the answer I'm looking for, cheers!
    – Earl Sven
    Commented Apr 3, 2018 at 10:45
  • Is an intermittent stream still a stream when it's dried up? / Humour (dry humour) aside, the whole problem of the essence of a river, body, mountain, lake, lump of cheese as it changes over time is a philosophical one. The language used to describe it is bound to be imprecise (if only at the level of an unworkably broad definition). 'Lake Ontario as at 14:22:56 on the 17th March 2000'. (Does one include the algae?) Commented Apr 3, 2018 at 11:02
  • In the UK, such an item is often referred to as Trigger's Broom, after a character in the TV sitcom Only Fool's and Horses. See this video for the original clip - youtube.com/watch?v=BUl6PooveJE Commented Apr 3, 2018 at 16:05

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