Full Idea
To know 'who he is', we must know the order of rank the innermost drives of his nature stand in relative to one another.
Gist of Idea
The ranking of a person's innermost drives reveals their true nature
Source
Friedrich Nietzsche (Beyond Good and Evil [1886], §006)
Book Reference
Nietzsche,Friedrich: 'Beyond Good and Evil', ed/tr. Hollingdale,R.J. [Penguin 1973], p.20
A Reaction
This is clearly an essentialist view of a person, as having a 'nature', which is 'inner', and which we can try to specify. Ranking drives and values seems a good proposal for getting at it. I'm also intrigued by what people find interesting.