Our etheric body is very complex and contains all our memories, ready to present them to us when we recall them. Even those things that have sunk down into the depths of the soul, things we are not aware of in waking consciousness, are contained in the etheric body in some way. Our whole life in this incarnation is retained in the etheric body, is really present in it.
Of course, this is very difficult to imagine, but it is true nevertheless. Imagine you were to talk all day long, as some people do, and everything you said was recorded on records. When the first record is full, you take a second one, then a third, and so on. The number of records would depend on how much you spoke. Now if someone collected all the records, everything you had said would be nicely preserved on records at the end of the day.
Then, if someone played them, everything you said during the day would be heard again. In a similar way, all our memories are retained in the etheric body. Under the special conditions of sleep one part of the etheric body appears before us, as though — to stay with this metaphor — we took one record from the collection and played it; this is the most common kind of dream. Thus our consciousness weaves in our own etheric body.
Source: Rudolf Steiner – GA 154 – UNDERSTANDING THE SPIRITUAL WORLD (PART ONE) – Berlin, April 18, 1914
Translated by Christian von Arnim and edited by Joachim Reuter