seity

The first is that great Principle of Seïty, or Selfness, as it may be called, innate to Man, which attaching him to the Prolongation of his own Existence more than to any other thing in the Universe, keeps his Eyes, his utmost Attention, continually fixed upon this Object; and compels him to make it the very Point, the Purpose of all his Advances and Proceedings; notwithstanding it does not permit him to distinguish the safest Paths to it from the dangerous ones.

Seity, sē′i-ti, n. something peculiar to one's self.

The learned Scotus, to distinguish the race of mankind, gives every individual of that species what he calls a "seity," something peculiar to himself, which makes him different from all other persons in the world.