He's wearing a heavy fur coat, because he's so skinny. And clearly, it's autumn outside. Sensible.

Unfunny jokes aside, the caption plusquamperfectum reminds me of the linguistic tense. A tense which was never really well explained to me in German (Plusquamperfekt).

Wikipedia lists it to mean "used to refer to an occurrence that at a past time had already been started (but not necessarily completed)". In the context of this painting, it's an apt metaphor for the process of death, which began at birth.