For it is thus that man is not plant, but man. He has the faculty, time and again to destroy the form as soon as it arises; for he excretes the carbon, bound to the oxygen, as carbonic acid. Carbon in the human body would form us too stiffly and firmly — it would stiffen our form like a palm. Carbon is constantly about to make us still and firm in this way, and for this very reason our breathing must constantly dismantle what the carbon builds. Our breathing tears the carbon out of its rigidity, unites it with the oxygen and carries it outward. So we are formed in the mobility which we as human beings need. In plants, the carbon is present in a very different way. To a certain degree it is fastened — even in annual plants — in firm configuration. (Steiner 2007:23)
But we must now go farther. I have placed two things side by side; on the one hand the carbon framework, wherein are manifested the workings of the highest spiritual essence which is accessible to us on Earth: the human Ego, or the cosmic spiritual Being which is working in the plants. Observe the human process: we have the breathing before us — the living oxygen as it occurs inside the human being, the living oxygen carrying the ether. And in the background we have the carbon-framework, which in the human being is in perpetual movement. These two must come together. The oxygen must somehow find its way along the paths mapped out by the framework. Wherever any line, or the like, is drawn by the carbon — by the spirit of the carbon — whether in man or anywhere in Nature there the ethereal oxygen-principle must somehow find its way. It must find access to the spiritual carbon-principle. Flow does it do so? Where is the mediator in this process? (Steiner 2007:23)
But now, all that is thus developed in the living creature, structurally as in a fine and delicate design, must eventually be able to vanish again. It is not the Spirit that vanishes, but that which the Spirit has built into the carbon, drawing the life to itself out of the oxygen as it does so. This must be able once more to disappear. Not only in the sense that it vanishes on Earth; it must be able to vanish into the Cosmos, into the universal All. (Steiner 2007:26)
STEINER, Rudolf. 2007. The Agriculture Course. (Trans.: George Adams) Shrewsbury: Wilding & Son Ltd.