Ernst writes that Steiner used imagination and insight as a basis for his ideas, drawing mystical knowledge from the occult Akashic Records, a work which is supposedly situated on the astral plane, and which Steiner said was accessible to him via his intuitive powers. On this basis, Steiner proposed "associations between four postulated dimensions of the human body (physical body, etheric body, astral body, and ego), plants, minerals, and the cosmos". Steiner also proposed a connection betweens planets, metals and organs so that, for example, the planet Mercury, the element mercury and the lung were all somehow associated. These propositions form the basis of anthroposophical medicine.