We have often brought to mind that man as we know him in his present form is, to begin with, a fourfold being; that he consists of the physical, etheric and astral bodies and the “I.” To spiritual vision these four principles appear in their external form as if the human physical body is enclosed in the centre like a kind of kernel. During the day this physical body is permeated by the so-called etheric or life-body which projects very slightly round about the head as a luminous halo, but which also completely permeates the head; further down it becomes more cloudy and indistinct and the more it approaches the lower parts of man the less definitely does it show the form of the physical body.
Now these two principles of the human being are during the day enveloped by what we call the astral body, which projects on all sides like an ellipse, in the shape of an egg, and in its fundamental form it has luminous rays which look as if their direction really were from outside inward, as if they would penetrate from outside to the inner part of the man. Within this astral body are outlined a great number of different figures, every possible kind of lines and rays, many like flashes of lightning, many in curious twists; all this surrounds the human being in the most varied manifestations of light. The astral body is the expression of his passions, instincts, impulses and desires, as also of all his thoughts and ideas. The clairvoyant consciousness sees portrayed in this astral body all that one calls soul-experiences, from the lowest impulses to the highest ethical ideals.
Then we have the fourth principle of the human being, which one might sketch as if something were sending in rays to a point lying about one centimetre (3/8 inch) behind the forehead. That would be the diagrammatic representation of the fourfold man. In the course of these lectures we shall see how the several parts are distinguished in the whole.
Source: Rudolf Steiner – GA 104 – The Apocalypse of St. John: Lecture II – Nuremberg, 19th June 1908
Translated by M. Cotterell