Slate has a fascinating, alluring, absorbing, beguiling, engrossing, enthralling, transfixing, and riveting essay about Peter Mark Roget and the thesaurus that bears his name:

Originally published in 1852, having been compiled over the course of more than four decades by the eponymous but strangely anonymous Peter Mark Roget, the thesaurus we know and love was not the first of its kind. Roget’s was the sixth or seventh in a line of, well, synonymous “ but not identical “ compendiums. Now, after a century-and-a-half career as a publishing juggernaut, the bound and beloved version is becoming a historical relic in the computer era.