This book was written to show that light is a primal element of life. All life originates and develops under the influence of the light of the sun, that "super terrestrial natural force" (Goethe). Sunlight influences the vital processes not onlyofthe plant (e. g., heliotropism, photosynthesis) and the animal (e. g., color change, maturation of the gonads) but of man as well. The human organism too reacts "heliotropically," as the 24 hour rhythm of the sleep-waking cycle demonstrates. of Artists have always perceived clearly the intensive stimulatory effect sunlight on their activity. One is...