As previously mentioned, the terrestrial human being constitutes the "life-unit" that the same being would most easily be able to investigate or observe. Let us therefore look at this "life-unit". We are witness to the fact that this has a physical or material body. This body constitutes its "aspect of substance". It consists of many different kinds of substance or matter. This matter is in turn to be expressed as a collection of energy-combinations or releases of force. In this body there is thus released digestion, oxidation, blood circulation, the development of muscle and so on, all of which are intended to sustain or maintain the body in question. Through the same body the "life-unit" corresponds with its surroundings, which means that it exerts an influence on its fellow beings, on other forms of matter and so on. It is this unfolding of energy that we call "creating". This creation thus constitutes the manifestation of the "life-unit"; and it is this manifestation that can be expressed as the "vibration of the life-unit". The "life-unit" can thus be expressed as a "fixed point" from which movements and vibration emanate.
      Just as the human being constitutes a "life-unit", so too does the animal constitute a "life-unit". The same is true of the plant. If we go further downwards in evolution it gets more difficult to distinguish the vibrations of the individual "life-units" from one another; and this apparently inextricable unfolding of energy or vibration is actually what we usually term "substance". Since people cannot separate the vibrations of the individual life-units from each other they tend to regard these vibrations or this "substance" as "life-less", which means without connection to I's. But the "substance" is far from being without connection to I's, and is just as far from being "lifeless". It is just as much an expression of the manifestations of the living beings as a collection of paintings, drawings or other man-made things. There is thus absolutely no "substance" without "life-units"; but where one cannot separate these from each other, one expresses their collective manifestation or appearance as "substance", "vibration" or "matter".