From Radiant Matter by Georg Blattman, a Christian Community priest:
Here we are concerned with the inmost secrets of matter and its transformation, for bread and wine become body and blood. But what is it that makes matter capable of being 'body' in the first place? In our bodies, for example, there are a number of different substances that go into making up our flesh, blood, bones, and so on, all of which can be chemically analyzed. But this is not a unique feature, for these substances can be found outside us too. And when we are dead and buried and our body begins to decay, these substances will all be somewhere in the Earth, where the rain can come and wash them away. They then belong to the Earth. So what is it that makes these substances our bodies? They are our bodies because, in a word, we are inside them. This 'piece of the world' is our tool, but it is much more than a hammer or a pair of pliers, for we are completely inside it, we identify with it. We have slipped into it right down to the individual molecules, so to speak. This is what makes 'matter' into 'body.'
In similar fashion, bread and wine become the body and blood of a divine spiritual being who slips into them, as we have slipped into the various parts of our bodies. When the bread is brought in at the beginning of the service, it is not yet body, but merely a piece of bread. It becomes body when Christ 'incarnates'--becomes flesh--in it.
And now we must perform the final act of uniting the bread and wine--the body and blood--that are already present, but still separate as a true polarity. It is essential that these two opposites be united--and here, man is necessary, for this process can take place only in the person who receives 'Communion' (which means 'becoming one'). The transubstantiated elements merge with man's own substance, but at the same time, bread and wine also become one. Thus those who question the need of giving the Communion in two forms ('Surely bread alone would be sufficient, Christ's blood is "included" in it as body') are only playing with words. For the goal of the whole process up until now has been that this polarity must finally be resolved. And through its resolution, primal unity is achieved on a new level--the counterpart of the origin of the first elements.
Every service at the altar gives the world a 'working model' of the way future evolution will renew the dying Earth.
Source: The Tree of Life and the Holy Grail by Sylvia Francke, pp. 61-62