Mental states of every kind, - sensations, feelings, ideas, - which were at one time present in consciousness and then have disappeared from it, have not with their disappearance absolutely ceased to exist.
Hermann EbbinghausIdeas which have been developed simultaneously or in immediate succession in the same mind mutually reproduce each other, and do this with greater ease in the direction of the original succession and with a certainty proportional to the frequency with which they were together
Hermann EbbinghausOne needs but to say that, in the case of an unfamiliar sequence of syllables, only about seven can be grasped in one act, but that with frequent repetition and gradually increasing familiarity with the series this capacity of consciousness may be increased
Hermann EbbinghausThe constant flux and caprice of mental events do not admit of the establishment of stable experimental conditions.
Hermann Ebbinghaus