What a satisfaction it is that the first momentous meeting with a being of the supersensible world is the meeting with our own being in its true reality which will guide us further in human evolution.
We may say that there is hidden within man a being that keeps careful watch and ward on the boundary which has to be crossed at the entrance to the supersensible world.
This spiritual being, hidden in man, which is man himself, but which he can as little perceive with ordinary consciousness as the eye can see itself, is the guardian of the threshold of the spiritual world.
We learn to recognise him at the moment at which we are not only actually he, but are also confronting him, as though we were standing outside him, and he were another being.
As with other experiences of supersensible worlds, it is the strengthened and reinforced faculties of the soul which make visible the guardian of the threshold.
For, setting aside the fact that the meeting with the guardian becomes raised into knowledge by clairvoyant spiritual sight, that meeting is not an event which happens only to the man who has become clairvoyant.
Exactly the same fact as is represented by this meeting happens to every human being every time he falls asleep, and we are confronting ourselves — which is the same thing as standing before the guardian of the threshold — for so long as our sleep lasts.
During sleep the soul rises to its supersensible nature. But its inner forces are not then strong enough to bring about consciousness of itself.
Source: Rudolf Steiner – GA 17 – A Road to Self-Knowledge and The Threshold of the Spiritual World: VIII. Concerning the Guardian of the Threshold and some Peculiarities of Clairvoyant Consciousness