The third principle of the human being is the so-called body of feeling, or astral body. It is the vehicle of pain and pleasure, of impulse, desire, passion, and so forth. An entity composed merely of a physical and an etheric body has nothing of all this, to which may be ascribed the term—sensation. The plant has no sensation. If many a learned man of our time concludes that plants have a certain power of sensation, from the fact that many of them respond to a stimulus, by movement, or in other ways, he merely shows that he does not know the essence of sensation. The point is, not whether the being in question responds to an outward stimulus, but rather whether the stimulus reflects itself through an inner experience, such as pleasure or pain, impulse, desire, etc. If this be not the standard of sensation, one would be justified in asserting that blue litmus paper has a sense of feeling for certain substances, because on coming into contact with them, it turns red.[2] Man has the astral body in common with the animal world only. It is thus the medium for the life of sensation and feeling. One must not fall into the error of certain theosophical circles and think that the etheric body and astral body consist merely of finer matter than that which exists in the physical body. For this would mean simply the materialisation of these higher principles of human nature. The etheric body is a form of living forces; it is composed of active forces, but not of matter—and the astral body or body of feeling is a form consisting of colored luminous pictures revolving within themselves.[3] The astral body differs in form and size from the physical body. It appears in man in the form of an oblong egg, in which the physical and the etheric bodies are embedded. It projects on all sides beyond these two like a luminous cloud. Now in the nature of man there is a fourth principle which he does not share with other earthly creatures. This is the vehicle of the human “I”. The little word “I” as we call it in English is a word that separates itself from all other words. He who duly reflects on the nature of this word, gains access at the same time to an understanding of human nature. Every other word may be used by all men in the same way to suit some corresponding object. Anyone can call a table “table,” any one can call a chair “chair,” but with the word “I” it is not so. No one can use it as an indication of some one else, for each person can only speak of himself as “I”. Never can the word “I” sound in my ears as a reference to myself. For a man in designating himself “I”, must name himself within himself. A being that can say to himself “I” is a world in himself. Those religions which are built up on the basis of Theosophy have always felt this. They have therefore said that with the “ego” the God begins to speak within—the God who, among lower beings, is manifested only from without in the surrounding phenomena.