Even Time magazine has realized that there’s something about blogs. People keep comparing them to online journals, but, as a bonafide medievalist, I can tell you they are more like common place books, as can McGee. Lance Koebel points to this Labyrinth entry defining the commonplace book. Swift, in his “A Letter of Advice to a Young Poet” suggests that
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.
Typically these books were compilations of brief passages, often with commentary, ordered topically or thematically—in short they were collections of commonplaces—or, for those with the Greek tongue, koinoi topoi, or loci communes, in the Latin .
The commonplace, as Richard Lanham tells us :
was a general argument, observation, or description a speaker could memorize for use on any number of possible occasions. So an American statesman who knows he will be asked to speak extempore on the Fourth of July might commit to memory reflections on the bravery of the Founding Fathers, tags from the Declaration of Independence, praise of famous American victories, etc. A few scattered traditional loci: death is common to all; time flies; the contemplative vs. the active life; the soldier’s career vs. the scholar’s; praise of a place as paradisiacal; the uses of the past; a short, celebrated life vs. a long, obscure one. (Lanham, Richard. Handlist of Rhetorical Terms (University of California Press: Berkeley, 1994).