Esoteric Lesson
"Anyone who wants to acquire a real view of four-dimensional space must perform very specific visual exercises. First, they form a very clear, deep view of water. Such a perception cannot be obtained easily; one must delve very deeply into the nature of water; one must, so to speak, crawl into the water. The second thing is to gain a perception of the nature of light; light is something that human beings know, but only insofar as they receive it from outside; Through meditation, one can obtain the inner counterpart of light, know where light comes from, and thus produce light oneself. This is possible for those who allow pure concepts to truly meditate on their soul, who have a way of thinking free of sensuality. Then the whole environment appears to them as flooding light, and now they must, as it were, chemically combine the mental image they have formed of water with that of light. This water, completely permeated by light, is a substance that alchemists called “mercury.” However, alchemical mercury is not ordinary mercury. First, one must awaken within oneself the ability to produce mercury from the concept of light. Mercury, light-permeated water power, is what one then possesses. This is the one element of the astral world.
Cite:
GA 266b/1911-01-17/p023 · edition English