We claim to know that motivation comes from either intrinsic or extrinsic sources. But this isn’t knowledge, it’s formulae. It’s circular reasoning – knowledge of the results of a presupposition. Of course any such assumption will be self-validating. You have to work, in our culture, to dismiss binary formulae and ask about things like reward or inspiration from the collective unconscious – things that don’t fit the formulae. What we “know” often interferes with what we could know, if we allowed for it.