Now there is a tremendous difference between a mental image whilst it  is in our memory and after we have forgotten it. So let us imagine a  mental picture we have formed of an  external impression, and now have in our consciousness. Then let us see  with our soul’s eye how it gradually disappears and is forgotten. It is  there nevertheless, and remains within the whole spiritual organism.  What does it do there? What does this so-called forgotten image do? It  has a very important function. From the moment of being forgotten it  begins to work in the right way on the free part of the etheric body we  have been speaking about, and make it serviceable for man. It is as  though it were not digested until then. As long as the human being uses  it for acquiring knowledge it does not yet work inwardly to bring life  into the free etheric organ. The moment it sinks into oblivion it begins  to work. So it can be said that work is continually in progress in and  upon the free part of the etheric body. And what is it that does the  work? It is the forgotten ideas! That is the great blessing of  forgetting! As long as a mental image remains in your memory you connect  it with an object. If you observe a rose and carry the mental image of  it in your memory, you connect the image of the rose with the outer  object. The image is thus chained to the external object and has to send  it its inner force. The moment you forget the image, however, you set  it free.
 Then it begins to develop germinal forces which work  inwardly on man’s etheric body. So our forgotten memories have great  significance for us. 
RUDOLF STEINER

