Human, All Too Human: A Book For Free Spirits / quote 56 of 58
The strength of feeling is no voucher for the validity of knowledge
What they claim is that through the medium of profound feelings one can penetrate deep into the soul of things (Innre), draw close to the heart of nature. But these feelings are deep only in so far as with them are simultaneously aroused, although almost imperceptibly, certain complicated groups of thoughts (Gedankengruppen) which we call deep: a feeling is deep because we deem the thoughts accompanying it deep. But deep thought can nevertheless be very widely sundered from truth, as for instance every metaphysical thought. Take from deep feeling the element of thought blended with it and all that remains is strength of feeling which is no voucher for the validity of knowledge, as intense faith is evidence only of its own intensity and not of the truth of that in which the faith is felt.