itself

it; A thing as the object of a verb or preposition that also appears as the subject

When the opportunity presented itself, no feasible course of action suggested itself (to us).

The researchers posit that something they call the “hipster effect” asserts itself in human populations no matter how individualistic we imagine ourselves to be, because it’s individuality itself that sparks conformity.

it; used to intensify the subject, especially to emphasize that it is the only participant in the predicate

The door itself is quite heavy.

Beautie alone is a ſoveraigne remedy againſt feare,griefe,and all melancholy fits; a charm,as Peter de la Seine and many other writers affirme,a banquet it ſelfe;he gives inſtance in diſcontented Menelaus that was ſo often freed by Helenas faire face: and ʰTully, 3 Tusc. cites Epicurus as a chiefe patron of this Tenent.

it; used to refer back to an earlier subject

The oil by degrees gets covered with a curdy mass, which after some time settles to the bottom, while itself becomes limpid and colorless.