There is a difference between weariness and depression.

And another difference that I've had to mention to a few people is the difference between acute and chronic versions of depression. Unlike many people, the Black Dog doesn't hang around with me. It is a relatively rare visitor; it comes in, hounds at my ankles for several days, and forces me to reassess my situation.

I guess that latter part is the metaphysical dog biscuit. Because then it leaves, satisfied.