Full Idea
We are pleased to flatter ourselves with the false claim to a nobler motive, but in fact we can never, even by the most strenuous self-examination, get to the bottom of our secret impulsions.
Gist of Idea
We may claim noble motives, but we cannot penetrate our secret impulses
Source
Immanuel Kant (Groundwork of the Metaphysic of Morals [1785], 407.26)
Book Reference
Kant,Immanuel: 'The Moral Law (Groundwork of Morals)', ed/tr. Paton,H.J. [Hutchinson 1948], p.72
A Reaction
Sounds more like Nietzsche than Kant. If some impulsions are totally hidden from us, then they are presumably irrelevant to any rational or moral thinking. Look at the deeds.