337. But as nerves are "conductors" for the individual's psychic or spiritual forces – that is to say, his thought-energies – and these "conductors", as stated above, become frayed or more or less injured by the events and mental functions of a whole day, then they gradually become more and more useless as "conductors" or carriers of the mental functions, and therefore the individual correspondingly reaches a state where he has to struggle to keep himself conscious. Such a state is called "sleepiness". But at last the "tiredness" or injuries to the nerves become so dominating that the individual is no longer able to keep awake. He drifts over into a prolonged state of "unconsciousness". We call this condition "sleep". While in this state there is no mental activity in the physical brain and consequently no further "current" through the physical nerves. But when the said "current" ceases in this way, then the wear and tear on brain and nerves also ceases. These then begin to heal. The injuries are repaired. The microscopic sores and wounds disappear. In the course of a few hours all the damage is repaired. And with this reparation the individual's mental activity begins anew. Spiritual forces or mental energies are carried into the physical nervous system and the function of consciousness is at work again. We say of an individual in such a situation that he is "waking up". With this awakening, his day-conscious experience of physical existence asserts itself. Physical existence appears, then, in two variations, namely as a condition of being "awake" and a condition of being "asleep". While the "awake" part of physical existence is connected with light or daytime, the "sleeping" part of that same existence is connected with darkness or night-time. And naturally it is because of this that these two conditions are called respectively "day-consciousness" and "night-consciousness".
      The reason that terrestrial beings have to experience existence in this way – either in an "awake" or a "sleeping" condition – is entirely to enable their physical bodies to be maintained in good order. This resting time can only be fully effective through total cessation of the "awake functions of consciousness". The energy which supports these functions with regard to terrestrial man is, of course, "gravity-energy" or "explosive energy", that is to say the energy which causes the greatest wear and tear in the nervous system and which consequently requires the greatest amount of sleep in order to repair the frayed and damaged nerves. Of all the beings in existence, then, it is terrestrial beings who require the greatest amount of sleep, that is, they find themselves in the longest state of "night-consciousness". But gradually, as the individuals develop and begin to make more and more use of higher energies, that is to say energies which are a contrast to gravity-energy, then the damage done to the nerves becomes less and less. This again means that there will be less and less to heal. And therefore one sleeps correspondingly less. And so the individual's day-consciousness expands accordingly and will one day almost dissolve night-consciousness so that the latter will be of only quite a latent nature. And then the individual's existence will be of a completely different form from the present one.
      But as long as the individual still finds himself in the animal kingdom and has to use the damaging energy over which he has limited control, then his existence and welfare is conditioned by rather extensive periods of night-consciousness so that the damage can be repaired.