Bookmarks before browsers
These four medieval bookmarks are 500-700 years old, yet they are smarter than what we use for our modern books - or even in our web browsers. Some just help you find your way back to a certain page, but others do so much more: they mark text column and line, in addition to the page. The lower one, for example, is like a computer that you program. Sliding it up and down, and turning its disk, means you will find your way back to a very specific place: the very line where you left off the day before.
More information on these rare devices and how they work in this blog I wrote about them.
Pics: Leiden, University Library, BPL 2001 (top); Utrecht, UB, MS 146 (bookmark labeled “B”); Amsterdam, Universiteitsbibliotheek, MSS I G 56-57 (heart-shaped bookmarks); and Harvard, Houghton Library, MS 277 (bottom).