'Itself' in the Bible

each man's work will be revealed. For the Day will declare it, because it is revealed in fire; and the fire itself will test what sort of work each man's work is.

Doesn't even nature itself teach you that if a man has long hair, it is a dishonor to him?

doesn't behave itself inappropriately, doesn't seek its own way, is not provoked, takes no account of evil;