In 1953, Solomon Pottesman held what appeared to be an ordinary, albeit very old, manuscript in his hands. As he carefully undid the wrappings on "Certaine sermons", which was published in 1637, two leaves of tattered parchment fell out.Pottesman, an eccentric and prolific book collector known in the trade as "Inky", immediately knew that something exciting was afoot. The yellowed pages were scribbled from edge to edge with florid, archaic handwriting – rows of book titles, with crossings out and lines drawn across whole sections, as though the writer were making an informal list. On closer inspection, that is exactly...