The school-boy doesnt force himself to learn his vocabularies and rules altogether at night, but knows that be must impress them again in the morning.
Hermann EbbinghausA poem is learned by heart and then not again repeated. We will suppose that after a half year it has been forgotten: no effort of recollection is able to call it back again into consciousness.
Hermann EbbinghausThe constant flux and caprice of mental events do not admit of the establishment of stable experimental conditions.
Hermann EbbinghausOften, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily.
Hermann Ebbinghaus