Rudolf Steiner:
14. The second form of the ‘I’ — first of the three forms that were indicated in the last section — appears as a ‘picture’ of the I. When we become aware of this picture-character, a light is also thrown on the quality of thought in which the ‘I’ appears before the ordinary consciousness. With all manner of reflections, men have sought within this consciousness for the ‘true I.’ Yet an earnest insight into the experiences of the ordinary consciousness will suffice to show that the ‘true I’ cannot be found therein. Only a shadow-in-thought is able to appear there — a shadowy reflection, even less than a picture. The truth of this seizes us all the more when we progress to the ‘I’ as a picture which lives in the etheric body. Only now are we rightly kindled to search for the ‘I,’ for the true being of man.
15. Insight into the form in which the ‘I’ lives in the astral body leads to a right feeling of the relation of man to the spiritual world. For ordinary consciousness this form of the ‘I’ is buried in the dark depths of the unconscious, where man enters into connection with the spiritual being of the Universe through Inspiration. Ordinary consciousness experiences only a faint echo-in-feeling of this Inspiration from the wide expanse of the spiritual world, which holds sway in depths of the soul.
16. It is the third form of the ‘I’ which gives us insight into the independent Being of man within a spiritual world. It makes us feel how, with his earthly-sensible nature, man stands before himself as a mere manifestation of what he really is. Here lies the starting-point of true Self-knowledge. For the Self which fashions man in his true nature is revealed to him in Knowledge only when he progresses from the thought of the ‘I’ to its picture, from the picture to the creative forces of the picture, and from the creative forces to the spiritual Beings who sustain them.
Source: http://wn.rsarchive.org/GA/GA0026/English/RSP1973/GA026_index.html