“It operates by association. With one item in its grasp, it snaps instantly to the next that is suggested by the association of thoughts, in accordance with some intricate web of trails carried by the cells of the brain.”
Vannevar Bush, As We May Think (1945) · Section 6, on the human mind · read it
Kept because it is the design brief for the web, the wiki and this book, written in 1945. Filing systems sort; minds link. A commonplace book is an attempt to keep notes the way the mind keeps them.