The Totality of a Man's Experience Makes Him Who He Is

 The will is first and original; knowledge is merely added to it as an instrument belonging to the phenomenon of the will. Therefore every man is what he is through his will, and his character is original, for willing is the basis of his inner being. Through the knowledge added to it, he gets to know in the course of experience what he is; in other words, he becomes acquainted with his character. Therefore he knows himself in consequence of, and in accordance with, the nature of his will, instead of willing in consequence of, and according to, his knowing, as in the old view." - Arthur Schopenhauer, The World as Will and Representation, Page 292 and 293

One of the problems with some of the rationalist philosophers is that they often become combatibilist.

Arthur here is teaching that our being is the will. We are who we are in eternity past. When we enter this life which is time and space, we go through life in successions. Thus as we learn more and more we get to know ourselves. Thus who we are and what we chose in eternity past becomes clear to us as time goes on.

It is similar to Leibniz thoughts.

G.W. Leibniz says, "Since this is so, we can say that the nature of an individual substance or of a complete being is to have a notion so complete that it is sufficient to contain and to allow us to deduce from it all the predicates of the subject to which this notion is attributed. An accident, on th other hand, is a being whose notion does not include everything that can be attributed to the subject to which the notion is attributed. Thus, taken in abstraction from the subject, the quality of being a king which belongs to Alexander the Great is not determinate enough to constitute an individual and does not include the other qualities of the same subject, not does it include everything that the notion of this prince includes. On the other hand, God, seeing Alexander's individual notion or haecceity, sees in it at the same time the basis and reason for all the predicates which can be said truly of him, for example, that he vanquished Darius and Porus; he even knows a priori (and not by experience) whether he died a natural death or whether he was poisoned, something we can know only through history. Thus when we consider carefully the connection of things, we can say that from all time in Alexander's soul there are vestiges of everything that has happened to him and marks of everything that will happen to him and even traces of everything that happens in the universe, even though God alone could recognize them all." - Discourse on Metaphysics, Page 8

In other words some qualifiers can be given to several different people. Such as King can be given to Alexander and David. However, what makes up Alexander is the sum total of his parts.