Commonplace books (or commonplaces) emerged in the 15th century with the availability of cheap paper for writing, mainly in England. They were a way to compile knowledge, usually by writing information into books. They were essentially scrapbooks filled with items of every kind: medical recipes, quotes, letters, poems, tables of weights and measures, proverbs, prayers, legal formulas. Commonplaces were used by readers, writers, students, and humanists as an aid for remembering useful concepts or facts they had learned. Each commonplace book was unique to its creator's particular interests.
By the 1600s, commonplacing had become a recognized practice that was formally taught to college students in such institutions as Oxford. The commonplace tradition in which Francis Bacon and John Milton were educated had its roots in the pedagogy of classical rhetoric, and “commonplacing” persisted as a popular study technique until the early twentieth century. Both Ralph Waldo Emerson and Henry David Thoreau were taught to keep commonplace books at Harvard University (their commonplace books survive in published form). Commonplacing was particularly attractive to authors. Some, such as Samuel Taylor Coleridge and Mark Twain, kept messy reading notes that were intermixed with other quite various material; others, such as Thomas Hardy, followed a more formal reading-notes method that mirrored the original Renaissance practice more closely. The older, "clearinghouse" function of the commonplace book, to condense and centralize useful and even "model" ideas and expressions, became less popular over time.
"Commonplace" is a translation of the Latin term locus communis which means "a theme or argument of general application", such as a statement of proverbial wisdom. In this original sense, commonplace books were collections of such sayings, such as Milton's commonplace book. Scholars have expanded this usage to include any manuscript that collects material along a common theme by an individual.
Critically, many of these works are not seen to have literary value to modern editors. However, the value of such collections is the insights they offer into the tastes, interests, personalities and concerns of their individual compilers.
From the standpoint of the psychology of authorship, it is noteworthy that keeping notebooks is in itself a kind of tradition among litterateurs. A commonplace book of literary memoranda may serve as a symbol to the keeper, therefore, of the person's literary identity (or something psychologically not far-removed), quite apart from its obvious value as a written record. That commonplace books (and other personal note-books) can enjoy this special status is supported by the fact that authors frequently treat their notebooks as quasi-works, giving them elaborate titles, compiling them neatly from rough notes, recompiling still neater revisions of them later, and preserving them with a special devotion and care that seems out of proportion to their apparent function as working materials.
Producing a commonplace is known as commonplacing.
Some modern writers see blogs as an analogy to commonplace books.