Several of Archimedes’s treatises were found on a palimpsest, a manuscript that had been scraped and washed so that another text could be written over it, thus reusing the expensive parchment. Reusing parchment was a common practice in the Middle Ages, but the original text can sometimes be reconstructed. Using digital processing with several types of light and X-rays to study this thirteenth-century-C.E. prayer book, scientists were slowly able to decipher the texts by Archimedes that were underneath, including one that had been completely lost. (Image by the Rochester Institute of Technology. )