Full Idea
Man is necessity down to his last fibre, and totally 'unfree', that is if one means by freedom the foolish demand to be able to change one's 'essentia' arbitrarily, like a garment.
Gist of Idea
It is absurd to think you can change your own essence, like a garment
Source
Friedrich Nietzsche (Philosophy in the Tragic Age of the Greeks [1873], p.7), quoted by Brian Leiter - Nietzsche On Morality 2 'Realism'
Book Reference
Leiter,Brian: 'Nietzsche On Morality (2nd Edn)' [Routledge 2015], p.40
A Reaction
This is the big difference between the existentialism of Nietzsche and the more famous Sartrean approach, where the idea of being able to remake your essence is the most exciting and glamorous proposal. I'm with Nietzsche.