Nitrogen, as she works in the life of Nature, has so to speak four sisters, whose working we must learn to know at the same time if we would understand the functions and significance of nitrogen herself in Nature’s so-called household. The four sisters of nitrogen are those that are united with her in plant and animal protein, in a way that is not yet clear to the outer science of to-day. I mean the four sisters, carbon, oxygen, hydrogen and sulphur. (Steiner 2007:22)
To know the full significance of protein it will not suffice us to enumerate as its main ingredients hydrogen, oxygen, nitrogen and carbon. We must include another substance, of the profoundest importance for protein, and that is sulphur. Sulphur in protein is the very element which acts as mediator between the Spiritual that is spread throughout the Universe — the formative power of the Spiritual — and the physical. (Steiner 2007:22)
Seeing that sulphur‘s activity in the economy of Nature is so very fine and delicate, we shall, however, best approach it by first considering the four other sisters: carbon, hydrogen, nitrogen and oxygen. These we must first learn to understand; we shall see what they signify in the whole being of the Universe. The chemist of to-day knows little of these substances. He knows what they look like when he has them in his laboratory, but he knows practically nothing of their inner significance in the working of the Cosmos as a whole. The knowledge of modern chemistry about them is scarcely more than our knowledge of a man of whose outer form we caught a glimpse as we passed by him in the street — or maybe we took a snapshot of him, and with the help of the photograph we can now call him to mind. We must learn to know the deeper essence of these substances. What science does is scarcely more than to take snapshots of them with a camera. All that is said of them in scientific books and lectures is scarcely more than that. (Steiner 2007:22)
So then we have these five substances. They, to begin with, represent what works and weaves in the living — and in the apparently dead, which after all is only transiently dead. Sulphur, carbon, hydrogen, oxygen, nitrogen: each of these materials is inwardly related to a specific spiritual principle. They are therefore very different from what our modern chemists would relate. Our chemists speak only of the corpses of the substances — not of the real substances, which we must rather learn to know as sentient and living entities, with the single exception of hydrogen. Precisely because hydrogen is apparently the thinnest element — with the least atomic weight —it is really the least spiritual of all. (Steiner 2007:26)
STEINER, Rudolf. 2007. The Agriculture Course. (Trans.: George Adams) Shrewsbury: Wilding & Son Ltd.