There is a hidden plastic artist in carbon, and this plastician building the manifold forms that are built up in Nature — makes use of sulphur in the process. Truly to see the carbon as it works in Nature, we must behold the Spirit-activity of the great Universe, moistening itself so-to-speak with sulphur, and working as a plastic artist — building with the help of carbon the more firm and well-defined form of the plant, or again, building the form in man, which passes away again the very moment it comes into being. (Steiner 2007:23)
So you can have the following idea. Underlying all living things is a carbon-like scaffolding or framework — more or less rigid or fluctuating as the case may be — and along the paths of this framework the Spiritual moves through the World. Let me now make a drawing (purely diagrammatic) so that we have it before us visibly and graphically. (Diagram 6). I will here draw a scaffolding or framework such as the Spirit builds, working always with the help of sulphur. This, therefore, is either the ever-changing carbon constantly moving in the sulphur, in its very fine dilution — or, as in plants, it is a carbon-framework more or less hard and fast, having become solidified, mingled with other ingredients. (Steiner 2007:23)
STEINER, Rudolf. 2007. The Agriculture Course. (Trans.: George Adams) Shrewsbury: Wilding & Son Ltd.