It cannot be sufficiently emphasized that it is necessary for the observer of supersensible realms first to acquire a view by means of the above-mentioned logic, before he tries to approach the spiritual world through his own perception. He must also recognize how comprehensible the manifest world of the senses appears when it is assumed that the communications of spiritual science are correct. All experience in the supersensible world remains an insecure, even dangerous, groping, if the above-mentioned preparatory path is ignored. Therefore in this work the supersensible facts of earth evolution are first communicated, before the path to supersensible knowledge itself is dealt with.
We must also consider the fact that anyone who finds his way purely through thinking into what supersensible cognition has to impart is not at all in the same position as someone who listens to the description of a physical process that he himself is unable to observe, since pure thinking is itself a supersensible activity. Thinking, as a sensory activity, cannot of itself lead to supersensible occurrences. If, however, this thinking be applied to the supersensible occurrences described by supersensible perception, it then grows through itself into the spiritual world. In fact, one of the best ways of acquiring one’s own perception in the supersensible realm is to grow into the higher world by thinking about the communications of supersensible cognition, for, entrance into the higher realms in this way is accompanied by the greatest clarity of perception. For this reason a certain school of spiritual-scientific investigation considers this thinking the most excellent first stage of all spiritual-scientific training.
Source:Rudolf Steiner – GA 13 – An Outline of Occult Science – IV. The Evolution of the Cosmos and Man
Translated by Maud and Henry B. Monges and revised for this edition by Lisa D. Monges.