One kind [of depression] is low-grade and sometimes gets called
or simple melancholy.
It's a kind of
spiritual torpor in which one loses the ability to feel pleasure or
attachment to things formerly important.... Kate Gompert's always
thought of this anhedonic state as a kind of radical abstracting of
everything, a hollowing out of stuff that used to have affective
content.... Everything becomes an outline of the thing. Objects
become schemata. The world becomes a map of the world. An anhedonic
can navigate, but has no location.
-- David Foster Wallace. Infinite Jest (1996) p.692-693