Dr Lucia Knoles, Assumption College: Commonplace Books: “a vital tool of erudition” (and why you’re going to be assigned one for my survey class)
She quotes Confucius:
If language is not correct, then what is said is not what is meant;
if what is said is not what is meant, then what must be done remains undone;
if this remains undone, morals and art will deteriorate;
if justice goes astray, the people will stand about in helpless confusion.
Hence there must be no arbitrariness in what is said.
This matters above everything.
Denise at Frugal Homeschooling: Keeping a Commonplace Book
A commonplace book is what a provident poet cannot subsist without, for this proverbial reason, that “great wits have short memories:” and whereas, on the other hand, poets, being liars by profession, ought to have good memories; to reconcile these, a book of this sort, is in the nature of a supplemental memory, or a record of what occurs remarkable in every day’s reading or conversation. There you enter not only your own original thoughts, (which, a hundred to one, are few and insignificant) but such of other men as you think fit to make your own, by entering them there. For, take this for a rule, when an author is in your books, you have the same demand upon him for his wit, as a merchant has for your money, when you are in his.
— Jonathan Swift
“A Letter of Advice to a Young Poet”
She links to a how-to-make-one article at DIY Planner.
Alan Jacobs in First Things comments on the physical act of writing versus the ol’ Ctrl-C and Ctrl-V. “Wisdom that is not frequently revisited is wisdom wasted.”