224. As all mental functions are of an "electric" nature, they can only have physical release or reaction through a "transmitter" or "aerial system". It is a system of this kind that the individual has in his brain and nerves. It consists of energies partly physical and partly mental. Therefore it can be tuned to different grades of exactitude and so be brought into contact with equivalent degrees of physical or spiritual energies, that is to say energy waves. This means that through the brain and nervous system the individual is able to come into contact with the reaction of the interplay between his bodily structure and the basic energies; this reaction is the inevitable basis of manifestation or experience of life and should thus be considered as a release of "electric" energy waves which pass through the brain and nervous system. As long as they pass through the physical side of that system they are identical with the individual's sensations of the pleasant and the unpleasant. But terrestrial man cannot consciously follow his sensations, or these electric waves, further than into the brain and nervous system, because after they have passed through the physical side they are of the spirit in pure essence and thereafter can be experienced only by spiritual bodies which are at the stage the physical body used to be when it had not yet developed physical senses such as sight and hearing. This is why the individual cannot experience the reactions or the electric waves as realistic physical feelings further than just into the physical part of the brain and nervous system. But beyond this physical part the electric waves continue as "non-physical" and can be experienced by the individual only according to how far his spiritual bodies are developed in order to be able to react to these waves. However, the waves are not experienced through these bodies as physical sensations but on the contrary as "spiritual feelings", which is exactly the same as "thoughts" or "thought climates". Thus the brain and the nervous system constitute the individual's "gateway" to the spiritual world. In as far as terrestrial mankind's spiritual bodies are still undeveloped, he will remain a victim to the irrational belief that the "gateway" (the brain and nervous system) is the cause of his mental functions and so he is still unaware of the spiritual bodies or the true facts of the matter. This irrational belief is stimulated further by the effect of the fact that in the gateway to the spiritual world there are found certain small openings for special kinds of electric waves, meaning that in the brain and nervous system there are special centres or complexes for the various mental functions. The human being in question will suffer from an illusion in believing that these special centres or complexes are the actual cause of his functions, while the truth is that they are only specific organs for physically transmitting and receiving specific spiritual energy waves or vibrations. Just as the aerial is not the cause of the music or the lecture received through a radio set connected to it, but is merely a centre through which the electric form of the music or lecture can be received and brought further to other centres of the apparatus and there be translated back into its original form, so the brain and nervous system are in no way the cause of whatever visible manifestation may occur, but are simply parts of a system for transmitting and receiving the reactions between the individual's bodily structure and the basic energies in the form of electric waves. In the same way as the reception or transmission through a radio set is discordant if there is something wrong with any of its component parts, so the transmission of reactions through the brain and nervous system is also discordant if there is something the matter with the particular centres or complexes in that system. Such disharmonies in the mind of the individual are generally known under such terms as insanity, mental handicap or paralysis.