Below is an excerpt from Rudolf Steiner's book, "Theosophy: An Introduction to the Spiritual Processes in Human Life and in the Cosmos." 1994. Anthroposophic Press: Hudson, New York. Pg. 135-36.
"This is one of the fundamental ideas of ancient Indian Vedanta wisdom. The sage acquires during earthly life what other people experience only after death, namely the ability to grasp the thought that we ourselves are related to all things, the thought, "that is you." In earthly life this is an ideal that our thinking can aspire to, but in the country of spirit beings it is an immediate fact that becomes ever clearer as we gain spiritual experience. We become ever more aware that, in our essential being, we belong to the spiritual world. We perceive ourselves as spirits among spirits, as organs of the primal spirits. We feel in ourselves their word, "I am the primal spirit," or, in terms of Vedanta wisdom, "I am Brahman," that is, I am part of, an organ of, the primal being from which all beings spring. Thus we see that what we grasp during earthly life as a shadowy idea and the object of all wisdom's aspiration is a matter of direct experience in the spirit world. This idea can be thought during earthly life only because it is an actual fact in spiritual existence."