LUMEN. You will cease to be astonished, my old friend, if you will but reflect that light and sound are nothing else than two _modes of motion_. In order to appreciate either one or the other of these two modes of motion, you must (and that is sufficient) be endowed with an apparatus in correspondence with them, which might be only a simple nerve. The eye and the ear are the apparatus for your terrestrial nature. In another natural organisation the optic nerve and the auditory nerve form quite different organs. Besides, light and sound are not the only two modes of motion in nature. I can even say that light and sound are the result of your manner of feeling, and not of anything real. [Sidenote: Nature possesses myriads of modes of motion.] There are in nature not one, but ten, twenty, a hundred, a thousand different modes of motion. Upon the Earth you are so formed as to be able to appreciate chiefly these two, which constitute almost the whole of your life in its external relations. Upon other worlds there are other senses with which nature can be appreciated under its various aspects. Some of these senses take the place of your eyes and of your ears, and others are in touch with perceptions entirely foreign to those which are received by terrestrial organs. QUÆRENS. When you spoke to me just now of the men-plants in the world of Cygnus, the idea occurred to me to ask if earthly plants possess a soul? [Sidenote: Form determined by soul.] [Sidenote: Souls of plants.] LUMEN. Most certainly. Terrestrial plants are gifted with a soul just as much as are animals and men. Without a potential soul no organisation could exist. The _form_ of a plant is determined by its soul. An acorn and the kernel of a peach are planted side by side in the same soil, the same situation, under the same conditions; why should the first produce an oak and the second a peach tree? Because an organic force inherent in the oak will construct its special kind of vegetable, and another organic force, another soul inherent in the peach, will equally draw to itself other elements necessary for its special body, just as the human soul, in the construction of its body, uses the means put by nature at its disposal. Only the soul of the plant has not any self-consciousness. [Sidenote: Souls and atoms.] [Sidenote: Personality of the soul.]