Until the time of the last great revolution in men’s consciousness that took place in the 15th century, there was still a clear perception of the great difference that exists in the metals, as between those that are found in the human being and those that are found in Nature. When we set out to consider the various substances in man’s physical nature, certain metals show themselves in greater or less degree. For example, iron is present in the human organism, in combination with various other substances; magnesium is also present, and we could name many others. Before the 15th century men were keenly alive to the difference between such metals as these we have mentioned, that are found when we examine the human organism, and such metals as are present in external Nature but are not at any rate quickly apparent in the human organism. The men of these earlier times said: Man is a microcosm; whatever is present in the world outside him, in the macrocosm, is present in some form or other in him. And this was for them no mere general principle in the abstract: had they gone but a little way in initiation knowledge, it followed inevitably from what they knew of the nature of man and of the nature of the Universe. They knew that we can only come to a true understanding of man when we bring together in one the whole of Nature, with all her impulses, with all the substances that she contains. Then we have a picture, an imagination of the being of man. And a disturbing element enters the picture when we meet with something outside in Nature that cannot be found in man. (Steiner 2012:29)
STEINER, Rudolf. 2012. World History in the light of Anthroposophy. (Trans.: George Adams; Mary Adams; Dorothy Osmond) London: Rudolf Steiner Press.