Experimento patet quod ille qui iam acquisivit scientiam intelligibilem per species intellectas, non potest actu considerare illud cuius scientiam habet nisi occurrat ei aliquod phantasma. Et inde est quod laeso organo imaginationis impeditur homo non solum ab intelligendo aliqua de novo, sed etiam considerando ea, quae prius intellexit, ut patet in phreneticis.
"From experience it is clear that he who has already acquired intelligible knowledge through intellectual appearances, is not able actually to consider the knowledge he has unless some phantasm comes to mind. And this is why injury to the organ of imagination impedes a man not only in newly understanding something, but also in considering that which he has previously understood, as is clear in the mad."
De sensu tr. 2 [De mem. et remin.] l. 2 n. 4
The 'organ of imagination' is the brain.