Funes el memorioso

AKA "Funes, His Memory", "Funes the Memorious", "Funes the Elephant-Memoried." Borges short story about a man who never forgets.

Funes, we must not forget, was virtually incapable of general, platonic ideas. Not only was it difficult for him to see that the generic symbol "dog" took in all the dissimilar individuals of all shapes and sizes, it irritated him that the "dog" of three-fourteen in the afternoon, seen in profile, should be indicated by the same noun as the dog of three-fifteen, seen frontally.
...
He had effortlessly learned English, French, Portuguese, Latin. I suspect, nevertheless, that he was not very good at thinking. To think is to ignore (or forget) differences, to generalize, to abstract. In the teeming world of Ireneo Funes there was nothing but particulars -- and they were virtually immediate particulars.

Collected Fictions, by Jorge Luis Borges, translated by Andrew Hurley, p. 136.