Full Idea
Appearance brings forth truth so long as it is used in experience, but as soon as it goes beyond the boundary of experience and becomes transcendent, it brings forth nothing but illusion.
Gist of Idea
Appearance gives truth, as long as it is only used within experience
Source
Immanuel Kant (Prolegomena to Any Future Metaphysic [1781], 292 n.III)
Book Reference
Kant,Immanuel: 'Prolegomena to Any Future Metaphysic', ed/tr. Lucas,Peter G. [Manchester UP 1971], p.50
A Reaction
This is the nearest I have found to Kant declaring for empiricism. It sounds something like direct realism, if experience itself can bring forth truth.