Every experience can be made intelligible by contrast. If there were no straight line we could not say high and low, or right and left. It is the straight line which makes us recognize them as such. If there were no sun we could not say south, north, east, or west. Therefore with every conception there must be some object to focus upon and with which to check our conception. With regard to deep sleep we have nothing in physical existence to compare it with, and therefore the experience of deep sleep remains only as a great satisfaction, joy, and upliftment, and as something that has vitalized us and created energy and enthusiasm. This shows that there is something we have received from it. We do not come back empty-handed from there; we have gained something we cannot obtain from the physical plane. We get something we cannot interpret in everyday language, more precious, more valuable and vital than anything from the physical and mental planes.