2. Consciousness in Sleeping and Waking States

We can, as you see, trace the alternation between sleeping and waking to another cause, and say that we live in successive cycles, in one of which our interest is awake to the world outside us, and in the other to our inner world. This alternation between outer and inner is one that belongs every bit as much to our life as the fact that the sun shines on the earth and then goes down, leaving it in darkness, belongs to the earth's life. In the latter case the spatial constellation is the factor involved in the alternation between light and darkness, bringing about the cycle of daytime and nighttime.