Central to Brunner’s theory is the characterization of three different modes of mental activity:
1) Practical reason, which every human possesses, and which serves one’s normal needs
2) Spiritual/intellectual (geistig) thought, which rises above the relative truth residing in experience and in science, and strives toward a perception of the one eternal and absolute essence.
3) "Superstition"—pseudo-contemplation, which is the mode of contemplation of most ordinary men. Unfounded belief is a distortion of the spiritual faculty. While practical reason recognizes that the “relative” is only “relative,” superstition elevates what is relative to the status of the absolute.
Each of the three modes of thought consists of three specificates. In the practical understanding, the specificates are feeling, knowing and willing. In spiritual life, these are modified to become, respectively, art, philosophy and mysticism (love). Superstition distorts the specificates of spiritual life, transforming them into religion, metaphysics and moralism.
Brunner's intention is to contrast popular thought with spiritual/intellectual thought. His work Die Lehre von den Geistigen und vom Volke is a survey of the whole of human intellectual history seen from the point of view of this doctrine.
Brunner's ultimate objective was to prepare the way for the establishment of a community centered on the life of the mind, which would in turn open the way to the expansion of democracy.