It will be readily understood that it is impossible to mention in this book all the details of the earth’s evolution, as it has been spiritually perceived by occultists, in order to illustrate the way in which the supersensible world is reflected in the manifested. Nor was this what was intended when it was said that the unseen may everywhere be demonstrated by its manifest effects. It was meant rather that everything that man encounters may, step by step, become clear and comprehensible if he brings manifested events under the illumination of occult science. Only in a few characteristic instances will reference be made in the following pages to confirmations of the invisible by the manifest, in order to show how this may be done everywhere in the course of practical life, if desired. ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Pursuing the evolution of the earth backward according to the above method of scientific spiritual investigations we arrive at a spiritual condition of our planet. But if we go farther back along this path of research we find that everything spiritual had previously passed through a kind of physical incarnation. Thus we come upon a bygone physical planetary condition, which was afterwards spiritualized, and subsequently transformed into our earth by repeated materialization. Our earth is therefore presented to us as the reincarnation of a very ancient planet. But occult science can go back still farther; and it then finds the whole process twice repeated. Thus, our earth has passed through three previous planetary conditions separated by intermediate spiritual conditions of rest. The physical substance, however, proves to be finer and finer the farther back we follow the incarnations.