It will become increasingly clear to us how this earthly life is connected with spiritual life. We rely on nature, which is on a lower level than we are, for our nourishment. For some time after death, the dead derive their nourishment from the ideas and the unconscious emotions that we here on earth take into sleep with us. Those who have died perceive a tremendous difference between people who in their waking life are filled only with materialistic feelings and ideas and also take them into sleep, and others who are wholly filled with spiritual ideas while awake and who continue to be filled with them in sleep.
The two types of people are as different in their effect on the dead as a barren region where no food can grow, where people would starve, and a fruitful area that offers nourishment in abundance. For many years after death, the dead draw a vitality from the souls sleeping here on earth filled with spiritual content, a vitality that is similar, only transposed into the spiritual realm, to what we draw in our physical life from the beings of the kingdoms of nature below us. We literally turn ourselves into fruitful pastures for the dead when we fill ourselves with the ideas of spiritual science. And we turn ourselves into barren ground and starve the dead if we take only materialistic ideas and attitudes into sleep.
Source: Rudolf Steiner – GA 154 – The Presence of the Dead on the Spiritual Path: Lecture Three: Awakening Spiritual Thoughts – Basel, May 5, 1914
Translated by Christian von Arnim