The Inner Life, Book I, 1938: Introduction "Friend, how can we discuss the Supermundane if energy is not yet realized as the foundation of Existence? Many will not understand at all what is meant by this, while others may think that they understand the significance of fundamental energy, but cannot think about it with clarity. It is necessary to train one's thought upon the idea of energy until the feeling of it becomes as real as the feeling about any solid object. We speak about feeling, because knowledge alone cannot provide an understanding of energy. Those who think of the Supermundane as the very Highest are correct. 'As below, so above.' Let this ancient saying serve as a guide to cognition of the forces of the Supermundane.' "