The movement of any part of our body is always effected in some way by the movement of the corresponding part of the skeleton. This in turn is set in motion by certain lengthenings and contractions of the appropriate part of the muscular system. Now the way in which the muscles cause the bones to move falls clearly under the category of mechanical causation. Certain portions of matter are caused to move by the movement of adjacent portions of matter. The picture changes when we look for the cause to which the muscles owe their movements. For the motion of the muscles is not the effect of any cause external to them, but is effected by the purely spiritual energy of our volition working directly into the physical substance of the muscles. What scientific measuring instruments have been able to register in the form of physical, chemical, electrical, etc., changes of the muscular substance is itself an effect of this interaction. To mark the fact that this type of causation is clearly distinguished from the type called mechanical, it will be well to give it a name of its own. If we look for a suitable term, the word 'magical' suggests itself. The fact that this word has gathered all sorts of doubtful associations must not hinder us from adopting it into the terminology of a science which aspires to understand the working of the supersensible in the world of the senses. The falling into disrepute of this word is characteristic of the onlooker-age. The way in which we suggest it should be used is in accord with its true and original meaning, the syllable 'mag' signifying power or might (Sanskrit maha, Greek megas, Latin magnus, English might, much, also master). Henceforth we shall distinguish between 'mechanical' and 'magical' causation, the latter being a characteristic of the majority of happenings in the human, animal and plant organisms.1 * Our next step in building up a truly dynamic picture of matter must be to try to obtain a direct experience of the condition of matter when it is under the sway of magical causation. Let us first remember what is the outstanding attribute with which matter responds to mechanical causation. This is known to be inertia. By this term we designate the tendency of physical matter to resist any outwardly impressed change of its existing state of movement. This property is closely linked up with another one, weight. The coincidence of the two has of late become a puzzle to science, and it was Albert Einstein who tried to solve it by establishing his General Theory of Relativity. The need to seek such solutions falls away in a science which extends scientific understanding to conditions of matter in which weight and inertia are no longer dominant characteristics. What becomes of inertia when matter is subject to magical causation can be brought to our immediate experience in the following way. (The reader, even if he is already familiar with this experiment, is again asked to carry it out for himself.)