The transformations in the things of the earth existing outside the human being occur with a certain relationship to humanity’s own evolution. After the seventh cultural period (5733-7893) has run its course, the earth will be visited by a catastrophe that may be likened to what occurred between the Atlantean and post-Atlantean ages, and the transformed earth conditions after this catastrophe will again evolve in seven time periods. Human souls who will then be incarnated will experience, at a higher stage, the union with the higher world experienced by the Atlanteans at a lower stage.
Only those human beings, however, in whom are incarnated souls that have developed in a manner possible through the influences of the Greco-Latin epoch (747 BC -1413 AD) and the subsequent fifth, sixth, and seventh cultural epochs of the post-Atlantean evolution will be able to cope with the newly formed earth conditions. The inner being of such souls will correspond to what the earth has then become. Other souls will then have to remain behind, whereas previously they would have had the choice of creating the conditions for advancement. Souls who will have created the possibility for themselves, in the transition from the fifth (1413-3573) to the sixth post-Atlantean period (3573-5733), of penetrating supersensible knowledge with the forces of intellect and feeling, will have the maturity for the corresponding conditions following the next great catastrophe. The fifth and sixth periods are, so to speak, decisive.
In the seventh, the souls who will have reached the goal of the sixth will develop correspondingly further; the other souls, however, will, under the changed conditions of the environment, find but little opportunity of retrieving what they have neglected. Only at some future time will conditions appear again that will permit this. — Evolution thus advances from age to age.
Source: Rudolf Steiner – GA 13 – An Outline of Occult Science – VI – The present and future of cosmic and human evolution
Translated by Maud and Henry B. Monges and revised for this edition by Lisa D. Monges.