On Memory And Reminiscense   

object of contemplation, while, in-relation to something else, it is

also a presentation of that other thing. In so far as it is regarded

in itself, it is only an object of contemplation, or a presentation;

but when considered as relative to something else, e.g. as its

likeness, it is also a mnemonic token. Hence, whenever the residual

sensory process implied by it is actualized in consciousness, if the

soul perceives this in so far as it is something absolute, it

appears to occur as a mere thought or presentation; but if the soul

perceives it qua related to something else, then,-just as when one

contemplates the painting in the picture as being a likeness, and

without having (at the moment) seen the actual Koriskos,

contemplates it as a likeness of Koriskos, and in that case the

experience involved in this contemplation of it (as relative) is

different from what one has when he contemplates it simply as a

painted figure-(so in the case of memory we have the analogous

difference for), of the objects in the soul, the one (the unrelated

object) presents itself simply as a thought, but the other (the

related object) just because, as in the painting, it is a likeness,

presents itself as a mnemonic token.

We can now understand why it is that sometimes, when we have such

processes, based on some former act of perception, occurring in the

soul, we do not know whether this really implies our having had

perceptions corresponding to them, and we doubt whether the case is or

is not one of memory. But occasionally it happens that (while thus

doubting) we get a sudden idea and recollect that we heard or saw

something formerly. This (occurrence of the 'sudden idea') happens

whenever, from contemplating a mental object as absolute, one

changes his point of view, and regards it as relative to something

else.

The opposite (sc. to the case of those who at first do not recognize

their phantasms as mnemonic) also occurs, as happened in the cases

of Antipheron of Oreus and others suffering from mental derangement;