Rudolf Steiner, September 16, 1907:
In a symbolism of great profundity, the world's whole being is now revealed to us in the symbol of the Holy Grail.
Let me set this seal before your eyes in a few words. The occultist who has acquainted himself with our world knows that space in the physical world is not simple emptiness, but something quite different. Space is the source from which all beings have, so to speak, physically crystallized. Imagine a cube-shaped, transparent glass vessel filled with water. Now imagine that certain cooling streams are led through this water so that it congeals in the most manifold forms into ice. This will give you an idea of the world's creation, of space, and of the divine creative Word spoken into it. The occultist presents this space into which the divine creative Word has been spoken as the water-clear cube.
Within this space various beings develop. The ones standing nearest to us can be characterized as follows. The cube has three perpendicular directions, three axes: length, height, and breadth. It thus represents the three dimensions in space. Now imagine the counter-dimensions to these three outside dimensions of the physical world. You may visualize this by imagining someone moving in one direction and colliding with someone else coming from another direction. Similarly, there is a counter-dimension to every dimension of space, so that in all we have six counter-rays. These counter-rays represent the primal beginnings of the highest human members. The physical body, crystallized from out of space, is the lowest. The spiritual, the highest, is the opposite counter-dimension.
In their development, these counter-dimensions first form themselves in a being that is best described when we let them flow together into the world of passions, sensual appetites, and instincts. This it is at first. Later, it becomes something else. It becomes ever more purified — we have seen to what height — but it issued from the lower impulses, which are here symbolized by the snake. The process of purification is symbolized by the counter-dimensions converging in two snakes standing opposite each other. As mankind purifies itself, it rises through what is called the world spiral. The purified body of the snake, this world spiral, has deep significance. The following example will give you an idea of it.
Modern astronomy is supported by two postulates of Copernicus, but a third has not been taken into account. Copernicus said that the Sun also moves. It advances in a spiral so that the Earth, following the Sun, moves in a complicated curve. The same is true for the Moon that revolves around the Earth. These movements are far more complicated than is assumed in elementary astronomy. You see here how the spiral has significance for celestial bodies, and these describe a form with which men will one day identify themselves. At that time, a man's generative power will be cleansed and purified, and his larynx will become his generative organ. What the human being will have developed as purified snake body will no longer work upwards, but from above downwards. The transformed larynx will become the chalice known as the Holy Grail. Even as one is purified, so also the other, which unites with this generative organ. It will be an essence of world force and of great cosmic essence. This world spirit in its essence is represented by the dove facing the Holy Grail. Here it symbolizes the spiritualized fructification that will be active out of the cosmos when men will have identified themselves with the cosmos. The complete creativity of this process is represented by the rainbow. This is the all-embracing seal of the Holy Grail. The whole gives the sense of the connection between world and men in a wonderful way, as a summation of the meaning of the other seals.
The world secret is found here as a circular inscription on the seal's outer edge, which shows how men in the beginning are born out of the primal forces of the world. Everyone, when he looks back, sees that he has gone through the process in the beginning of time that he goes through spiritually today when he is born anew out of the forces of consciousness. This is expressed in the Rose Cross by E. D. N., Ex Deo Nascimur, out of God I am born.
We have seen that within the manifest world a second is added to life, that is, death. That he find life again in this death, a man must find the death of the senses in the primal source of all that lives. This is the center of all cosmic development because we have had to experience death in order to gain consciousness. We will be able to overcome death when we find its meaning in the mystery of the Redeemer. Just as we are born out of God, so, in the sense of esoteric wisdom, we die in Christ — I. C. M., In Christo Morimur.
Because a duality is disclosed wherever something reveals itself, with which a third member must unite, the man who has overcome death will identify himself with the spirit that permeates the world, symbolized by the dove. He will rise from death and again live in the spirit — P. S. S. R., Per Spiritum Sanctum Reviviscimus.
Here stands the theosophical Rose Cross. It rays forth to those times in which religion and science will be reconciled.
Source: http://wn.rsarchive.org/Lectures/OccSigns/19070916p01.html