Full Idea
This hegemonicon (self-power) always determines the passive capability of men's nature one way or other, either for better or for worse; and has a self-forming and self-framing power by which every man is self-made into what he is.
Gist of Idea
There is a self-determing power in each person, which makes them what they are
Source
Ralph Cudworth (Treatise of Freewill [1688], §X)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.132
A Reaction
The idea that we can somehow create our own selves seems to me the core of existentialism, and the opposite of the Aristotelian belief in a fairly fixed human nature. See Stephen Pinker's 'The Blank Slate' for a revival of the old view.