A palimpsest keeps the writing it was scraped to erase

The geometry underneath the prayers

Sometime in the thirteenth century a monk took apart a book more than two centuries old and scraped the ink from its parchment. He cut the leaves down the middle, turned them ninety degrees, folded them in half, and bound the recycled skin into a prayer book he finished in 1229.²³ The pages he cleaned had carried a tenth-century Constantinople copy of Archimedes.³ The Greek word for what he had made says exactly this: palimpsēstos, "scraped again."¹ What the scraping could not do was make the older writing gone. Faint horizontal lines of geometry still ran beneath the monk's vertical columns of prayer, waiting for a reader equipped to see them.

Reading the erased layer

The erasure had never been complete. The first scribe wrote in an iron-based ink, and the iron had bitten into the skin. An X-ray beam could find the old letters by the metal they left behind, reading even pages a forger later hid under a painted icon.⁴ Multispectral imaging, working across infrared, visible, and ultraviolet light, recovered about 80 percent of the buried text.⁴ The scholar who first knew what he was looking at, Johan Ludvig Heiberg, had examined the book by eye and published its Archimedes between 1910 and 1915.³ Two of the seven treatises the book preserves, The Method and the Stomachion, survive nowhere else; On Floating Bodies survives here alone in its original Greek.²⁴

1. 10th c.

   A scribe in Constantinople copies seven works of Archimedes onto parchment.³

2. 1229

   A monk scrapes the parchment clean and completes a prayer book over it.³

3. 1906

   The Archimedes undertext is recognized beneath the liturgy.⁴

4. Oct. 29, 1998

   The book sells at Christie's in New York to an anonymous buyer for $2 million.³

5. 1999

   It arrives at the Walters Art Museum in Baltimore, and the imaging begins.⁴

The sense outgrows the parchment

Merriam-Webster carries a second sense that owes nothing to manuscripts: something with diverse layers apparent beneath the surface.¹ The figure is old. In 1845 Thomas De Quincey called the human brain "a natural and mighty palimpsest." Its "everlasting layers of ideas, images, feelings" each seem to bury the last, he wrote, "and yet, in reality, not one has been extinguished."⁵ Geographers took the picture to the ground. Canadian Geographic defines a palimpsest landscape as "a place or landscape in which something new is superimposed over traces of something preceding it." Its example is the tin-worked granite of west Cornwall, read as stacked layers of cultural and geological history.⁶ A programmer meets the same shape in a deleted file whose bytes linger on a disk until something else claims the space.

The layer that stayed

On the leaves the Walters imaged, the horizontal geometry of Archimedes still crosses the monk's vertical prayers, both legible at once.⁴ The scraping was meant to end the older text. It did not, and that failure is what the word now carries wherever it travels, to a coastline, a memory, a disk: writing that outlasts its own erasure.