Full Idea
At the beginning stands the great fateful error that the will is something which produces an effect - that will is a faculty.... Today we know it is merely a word.
Gist of Idea
The big error is to think the will is a faculty producing effects; in fact, it is just a word
Source
Friedrich Nietzsche (Twilight of the Idols [1889], 2.5)
Book Reference
Nietzsche,Friedrich: 'Twilight of the Idols and The Anti-Christ', ed/tr. Hollingdale,R.J. [Penguin 1972], p.38
A Reaction
This is despite Nietzsche's insistence that 'will to power' is the central fact of active existence. The misreading of Nietzsche is to think that this refers to the conscious exercising of a mental faculty.