Early Christian monks believed in something they called acedia. More colloquially, they called it the Noonday Devil, a name that essentially describes the concept. Acedia, for them, was different from ordinary depression in that it didn’t draw you into the dark, chaotic areas of your mind and heart, to have you diseased before your own complex and infinite depth; it was more of a flattening out, a dearth of energy, that put you into a semi-vegetative state that simply deadened all deep feeling and thoughts.