Full Idea
Strictly speaking there is no knowledge [science] without presuppositions; a philosophy, a 'faith', must always be there first of all, for knowledge to win from it a direction, a meaning, a limit, a method, a right to exist.
Gist of Idea
Scientific knowledge is nothing without a prior philosophical 'faith'
Source
Friedrich Nietzsche (On the Genealogy of Morals [1887], III.§24)
Book Reference
Nietzsche,Friedrich: 'On the Genealogy of Morals/ Ecce Homo', ed/tr. Kaufmann,Walter [Vintage 1969], p.151
A Reaction
He sees philosophers as the creators of this faith, and laughs at anyone who tries to set philosophy on a scientific basis.