Steiner emphasized that there is an objective natural and spiritual world that can be known, and that perceptions of the spiritual world and incorporeal beings are, under conditions of training comparable to that required for the natural sciences, including self-discipline, replicable by multiple observers. It is on this basis that spiritual science is possible, with radically different epistemological foundations than those of natural science. He believed that natural science was correct in its methods but one-sided for exclusively focusing on sensory phenomena, while mysticism was vague in its methods, though seeking to explore the inner and spiritual life. Anthroposophy was meant to apply the systematic methods of the former to the content of the latter