As any form of experience whatsoever is identical with the reaction to an interaction between two forms of energy, namely the concerned being's own energy and the energy of the being's surroundings, and as energy in turn, in the absolute sense, is the same as substance or matter, all existing experiences will in reality be based on matter and are thus "material". That it is not usual to perceive it in this way is due to the fact that matter appears in degrees of different density and with different characteristics. As the senses of the terrestrial human being are primarily built to react only through the interchange between the most dense degrees, then the other more rarefied degrees of energy become more and more gaseous until they eventually become totally invisible, in ratio to the distance they reach beyond the terrestrial human being's area of sensory perception. But this of course does not alter the fact that these degrees of energy do exist. And in daily life one therefore differentiates between visible and invisible energies.
      One calls the condensed energies "physical matter" and the gaseous energies "spirit", just as the area of the former energies is expressed as "the physical world" and the area of the latter is perceived as "the spiritual world". This latter world is thus also material, even though it is made up of refined energies or matter.
      The total substance or energy of the universe appears to the occult sight in seven different basic sorts, of which six directly affect the corresponding senses in the living beings, each with its own particular characteristics. What does one understand by senses? Senses are to be understood as the realities through which the interaction between the energy of the living being and the energy of its surroundings can be elicited. And it is the reaction of this interaction that becomes "the experience of life" for the being in question. The kind of reactions and thereby the kind of experience of life to which the same being is subject will depend upon the kind of basic energies for which its senses are constructed.
      As to the six basic kinds of energy, there are six corresponding different forms of interaction between the living being's own energy and the energy of its surroundings, which must of necessity have as a consequence six different general forms for the experience of life. The individual does not experience these six general forms at the same time but, on the contrary, only one at time. The living being has thus a period when its experience of life is promoted by the reactions from the first basic energy. When this promotion has culminated, its experience of life begins to be promoted by the reactions of the next energy and so on, until the sixth basic energy is reached. Then its experience of life begins to be promoted by the first basic energy again, but in a higher and more perfect form than the previous time, so that the individual constantly feels that he is moving towards higher and higher forms of existence. It is this movement we call "evolution".