When science and psychology arrive at a certain understanding, on that day knowledge will become complete. But then I use the word psychology in a specific sense, not in the sense in which it is generally understood. The psychology which is considered nowadays as a new philosophy is still in a primitive condition; what I mean by psychology is the bridge between material science and esotericism. But before going further into this subject I should mention that the terms matter and spirit are meant only for our convenience. As far as we perceive life as something tangible we call it matter; and what is not as tangible as a substance but is yet perceptible we call spirit. It is the knowledge of this spirit that we call psychology, whereas the knowledge which is gained neither by tangibility of substance nor by perception but by revelation is called esotericism. Thus we can divide the different aspects of knowledge into three groups: science, psychology, and esotericism. It is these three that make knowledge complete; and it is through these that one can hope to understand life more fully.