The nerd in me (okay, so all of me) got all excited when I found out that the concept of sandpaper turned out to have been around for centuries before the first real mass production of "glass paper" by John Oakey in 1833. There were even written warnings for counterfeit glass paper being sold on the streets of Paris in the mid 1700's.
The first actual patent for sandpaper production was in 1834 by Isaac Fischer, Jr. in Vermont and in 1916 3M invented the first wet/dry sandpaper. If you would like to read more than you ever wanted to know about the details of sandpaper you should give this engineering article a read C&EN Sandpaper. Go ahead click it, no one will be the wiser...you know you want to.
These videos cover the basics of sandpaper sharpening or the "scary sharp" method. I mention a couple of links in the videos which are below. Please feel free to leave a comment and check them out at the P.H.W. YouTube channel as well (link is below).
Scary Sharp Original Message
Lie Nielsen Sharpening Jig Alterations
Grit Comparison Chart - Fine-Tools.com
Grit Comparison Chart - StraightRazorPlace
Check these out in HD (where I appear ugly in high definition!) on my YouTube Chanel here: