I would have you imagine, then, that there exists in the mind of man a block
of wax... and that we remember and know what is imprinted as long as the
image lasts; but when the image is effaced, or cannot be taken, then we
forget or do not know.
- -- Plato, Dialogs, Theateus 191
[Quoted in "VMS Internals and Data Structures", V4.4, when
referring to image activation and termination.]