Here _it_ refers back to the whole sentence before it, or to the idea,
"any man's doing wrong merely out of ill nature."

(3) _As a grammatical subject, to stand for the real, logical
subject, which follows the verb_; as in the sentences,--

_It_ is easy in the world _to live after the world's opinion_.
--EMERSON.

_It_ is this _haziness_ of intellectual vision which is the
malady of all classes of men by nature.--NEWMAN.

_It_ is a pity _that he has so much learning, or that he has not
a great deal more_.--ADDISON.

(4) _As an impersonal subject in certain expressions which need no
other subject_; as,--

_It_ is finger-cold, and prudent farmers get in their barreled
apples.--THOREAU.

And when I awoke, _it_ rained.--COLERIDGE.

For when _it_ dawned, they dropped their arms.--_Id._

_It_ was late and after midnight.--DE QUINCEY.

(5) _As an impersonal or indefinite object of a verb or a
preposition_; as in the following sentences:--