This
http://benfry.com/traces/ is a rather cool visualization.
(WARNING: May take a little while to load) It shows sections (pages?)
of the book "On the Origin of Species" as they evolved over the 6
editions that Darwin edited during his lifetime.
One notable edit: "...the phrase “survival of the fittest” — usually
considered central to the theory and often attributed to Darwin —
instead came from British philosopher Herbert Spencer, and didn't
appear until the fifth edition..."
If you hover your mouse over the (illegible) columns, that local
portion of the text appears readably in a separate box.
Perhaps not surprisingly, this visualization technique reminds me of
watching a dynamic trace of computer memory pages. Words are words, I
guess. :/