He gathered them from the corners of his empire, some of them dating back to the third millenia BC, and created the first systematically organised library of the ancient world.
Unfortunately not even the "King of the Universe" can live forever, so when he died at the ripe old age of 42, there was dispute over his throne. The dispute and civil disruption came to an end in 612BC, when Babylon razed Ninevah to the ground, put torch to the library, and the Assyrian empire crumbled into ash and rubble. The library, it's contents and accumulated knowledge were lost in the sands of time.
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What happens when you burn down a wooden building with wooden shelves full of wax and paper and parchment and tens of thousands of raw clay tablets? That's right, tens of thousands of earthenware tablets that will last forever!
So, in 1839, when a young British archaeologist happened to be passing through Mesopotamia on his way to Ceylon, he had a poke around and discovered a library of cuneiform texts that included, among other things, the oldest epic narrative in the world, the Epic of Gilgamesh. But that's another story.
Time rolls on and leaves it's marks upon us with it's passing. It neither names nor counts the years, but the years are stamped indelibly in the grain of wood and the strata of the earth. For our brief time upon this earth we measure it, number it and arbitrarily dissect it and name the fragments we have cut it into.
I am only here for this one short life, seeing this day, this moment, through these eyes. I am neither a king nor am I Yanagi's unknown craftsman. So I leave my stamp upon the clay of my vessels, and beside it a mark to tell the year, for I have made these works in my time, they are unique, and though they may last for thousands of years, I will never pass this way again.