This shows that we have no right to imagine the earth without men, and to suppose that its cosmic conditions of being would then remain unaltered - any more than we can imagine a human being deprived of some essential-organ and remaining human. Mankind, and all the other kingdoms of nature, are bound up organically with the earth from the start of its existence. Moreover, just as the highest plants, seen with Goethe's eyes, are the spiritual originators of the whole realm of plants - the creative Idea determining their evolution - so we see man, the highest product of earth evolution, standing behind this evolution as its Idea from the first, and determining its course. The evolutionary changes which we observe in the earth and in man are in fact a single process, working through a variety of manifested forms. From this conception of the parallel evolution of earth and man light falls also on the historic event represented by van Helmont's discovery. Besides being a symptom of a revolution in man's way of experiencing the atmosphere, it speaks to us of some corresponding change in the spiritual-physical condition of the atmosphere itself. It was then that men not only came to think differently about air, but inhaled and exhaled an air that actually was different. To find out what kind of change this was, let us turn once more to man's own organism and see what it has to say concerning the condition under which matter is capable of being influenced by mechanical and magical causation respectively, in the sense already described. What is it in the nature of the bones that makes them accessible to mechanical causation only, and what is it in the muscles that allows our will to rouse them magically? Bones and muscles stand in a definite genetic relationship to each other, the bones being, in relation to the muscles, a late product of organic development. This holds good equally for everything which in the body of living nature takes the form of mineralized deposits or coverings. Every kind of organism consists in its early stages entirely of living substance; in the course of time a part of the organism separates off" and passes over into a more or less mineralized condition. Seen in this light, the distinction between bones and muscles is that the bones have evolved out of a condition in which the muscles persist, though to a gradually waning degree, throughout the life-time of the body. The substance of the muscles, remaining more or less 'young', stands at the opposite pole from the 'aged' substance of the bones. Hence it depends on the 'age' of a piece of matter whether it responds to magical or mechanical causation.