The Archimedes Palimpsest

Parchment was expensive in the medieval world, and a monk needing pages for a new prayer book did not always start with a blank sheet. In thirteenth century Byzantium, a scribe assembling a Euchologion, a book of prayers for the church's liturgy, took older manuscripts apart for their parchment, scraped the existing ink away as thoroughly as the technology of the day allowed, cut the larger sheets down, rotated them ninety degrees, and folded them to the new book's smaller size. One of the manuscripts fed into this recycling was a tenth century copy of seven mathematical treatises by Archimedes, the ancient Greek mathematician whose work on geometry, mechanics and what would later be called calculus had already been rare and precious even before a monk scraped it away to make room for prayers.

The erasure was thorough enough to fool centuries of readers, but not perfect. Faint ghost traces of the underlying Greek mathematics remained visible under the right conditions, and in 1906 the Danish philologist Johan Ludvig Heiberg spent days in Constantinople reading what he could of them with a magnifying glass, recognizing text from two treatises, the Method and the Stomachion, that survived nowhere else in the ancient record. The manuscript then vanished from scholarly view for most of the twentieth century, its exact whereabouts unknown, before resurfacing decades later in circumstances nobody studying it in 1906 could have predicted.

On 28 October 1998, a battered Byzantine prayer book crossed the block at Christie's in New York and sold for two million dollars to a bidder who chose to remain anonymous. The buyer was not paying for the prayer book. Everyone in the room understood the real object of value was the faint, mostly illegible traces of ancient Greek mathematics still visible beneath its liturgical text, the same erased Archimedes treatises Johan Ludvig Heiberg had partially read almost a century earlier before the manuscript disappeared from scholarly circulation.

What the anonymous owner did next mattered as much as the purchase itself. Rather than keeping the manuscript in private hands, unstudied, the buyer deposited it with the Walters Art Museum in Baltimore in 1999 and funded a conservation and imaging project that ran for more than a decade, using multispectral imaging and, for the most stubbornly hidden pages, X-ray fluorescence at a particle accelerator to read text no eye could recover directly. The project recovered far more of Archimedes' treatises than Heiberg had ever seen, along with the previously unsuspected texts of a lost speech by the orator Hyperides hiding in the same recycled parchment, and published everything openly online, turning a private acquisition into one of the more generous acts of modern manuscript scholarship.