Commonplace Books ~

"One forerunner of the diary has historically been used more to regard art than create it.  It was the practice of making a record of one's reading, or of whatever information came one's way, that gave rise to those diaries still known as commonplace books.  The special interest of those kept by artists is obvious:  What piece of reading or news may have triggered a particular line of verse, or perhaps a whole painting?  For writers, especially, commonplace books are the records of influence, but they have for centuries been kept by blocked writers and non writers as well."

~ A Book of One's Own People And Their Diaries, Thomas Mallon, Ticknor & Fields, 1984.

Note:  English Poet, John Milton (1608 - 1674), kept a commonplace book.  He drew on these notes for his later work.  Milton's commonplace book is now in the British Library.