Rudolf Steiner, from a lecture given September 30,1923:
"...withdrawing from the physical body, according to the methods you will find described in my books, and then being able to observe the effects of an outer object on the human physical organism; to observe how the ether forces, rising from within, seize on the physico-chemical process that takes place, for example, in the eye during optical perception. In reality, the act of exposing ourself in the ordinary way to the world in perception, even in scientific observation, does not affect us very deeply. But when a man steps out of himself in this way and confronts himself in the etheric body and possibly in the astral as well, and then sees ex postfacto how such a sense-process of perception or cognition came about — even though his spiritual nature had left his physical sense-nature — then he indeed feels a mighty, intensive process taking place in his spirituality. What he then experiences is real ecstasy. The world becomes immense; and what he is accustomed to seeing only in his outer circle of vision, namely, the zodiac and its external display of constellations, becomes something that arises from within him. If someone were to object that what thus arises might be mere recollections, this would only prove that he does not know the event in question; for what arises there are truly not recollections but mighty imaginations transfused by intuitions: here we begin to behold from within what we had previously seen only from without. As human beings we become interwoven with all the mysteries of the zodiac; and if we seize the favorable moment there may flash before us, out of the inner universe, the secret of Saturn, for example, in its passage across the zodiac. Reading in the cosmos, you see, consists in finding the methods for reading out of the inwardly seen heavenly bodies as they pass through the zodiac. What the individual planet tells us provides the vowels of the world-script; and all that forms around the vowels when the planets pass the zodiacal constellations gives us the consonants, if I may use this comparison. By obtaining an inner view of what we ordinarily observe only from the outside we really learn to know the essence of what pertains to the planets.
That is the way to become acquainted with Saturn, for example, in its true inner being. We see its population, which is the guardian of our planetary system's memory; everything that has ever occurred in our planetary system since the beginning of time is preserved by the spirits of Saturn as in a mighty cosmic memory...."