alan jacobs on the commonplace book:
Commonplace books became widely used in the early modern period, largely because literate people were discombobulated by the flood of information that the printing press had unleashed on them. (One 17th-century writer wailed, “We have reason to fear that the multitude of books which grows every day in a prodigious fashion will make the following centuries fall into a state as barbarous as that of the centuries that followed the fall of the Roman Empire.”) Some of these were just scrapbooks, the predecessors of today’s Everything Buckets, as Alex Payne has called them — applications like Evernote or DEVONthink — and would be places to store recipes, notes from sermons, remedies for common maladies … you know, everything.
But the other kind of commonplace book was different. Its goal was to gather a collection of the wisest statements, usually of the ancients, for future meditation. And here the key thing was to write the words in your own hand — by this means, by laboriously and carefully copying out the insights of people smarter than you, you could absorb and internalize their wisdom. Call it osmosis-by-handwriting. (Some people would copy out whole books by their favorite writers in the hopes of achieving some kind of voodoo transference of power.)
and elsewhere he says:
I think I can hazard this claim: Keeping a commonplace book is easy, but using one? Not so much. I started my first one when I was a teenager, and day after day I wedged open books under a foot of my ancient Smith-Corona manual typewriter and banged out the day’s words of wisdom. I had somewhat different ideas then of what counted as wisdom. The mainstays of that era—Arthur C. Clarke and Carl Sagan were perhaps the dominant figures—haven’t made any appearances in my online world. But even then I suspected something that I now know to be true: The task of adding new lines and sentences and paragraphs to one’s collection can become an ever tempting substitute for reading, marking, learning, and inwardly digesting what’s already there. And wisdom that is not frequently revisited is wisdom wasted.