VII. Inner Processes in the Human Organism. Sense-Perception, Breathing, Sleeping, Waking, Memory

Something of great significance for human life presents itself to us when we observe these processes. If our waking life was not interrupted by sleep, although impressions of the outer world would come to us, these impressions would last only for a short time. We could not develop a lasting power of memory. You know how fleetingly the pictures work in the senses as after-images. Processes activated more deeply in the organism continue to work for a longer time; but the after-effects would not continue for more than a few days if we did not sleep.