"So it isn't the original building?" I had asked my Japanese guide.
"But yes, of course it is," he insisted, rather surprised at my question.
"But it's burnt down?"
"Of course. It is an important and historic building."
"With completely new materials."
"But of course. It was burnt down."
"So how can it be the same building?"
"It is always the same building."
I had to admit to myself that this was in fact a perfectly rational point of view, it merely started from an unexpected premise. The idea of the building, the intention of it, its design, are all immutable and are the essence of the building. The intention of the original builders is what survives. The wood of which the design is constructed decays and is replaced when necessary. To be overly concerned with the original materials, which are merely sentimental souvenirs of the past, is to fail to see the living building itself.
From the book ‘Last Chance to See’, by Douglas Adams
See The Ship of Theseus Paradox at Wikipedia, where I found this passage, for more about the essence of things whose parts have been replaced.
Photo from that breathtaking site, The Tale of Genji