Acknowledging such a nucleus as constituting the very substance of Christianity, Eucken proceeds to show the necessity of preserving and unfolding the nucleus against the changes of Time. The nucleus has to be preserved over against Nature. It has been noticed in previous chapters how modern science has presented us with a view of Nature immensely vaster than that presented in Christian theology. Such a view has destroyed for ever a large number of the theological conceptions of the past. The earth has been reduced to a subsidiary place within the cosmos; and any attempt to return to the old conceptions is bought at too high a price. A new mode of thought in regard to the interpretation of the physical universe has come to stay, and the sooner the Christian Church comes to an understanding with it the better for the Church itself. And this new mode may be gladly accepted, because it cannot touch the nature and destiny of the _soul_ of man. We are not able to view the perfect circle of things, but we are able to [p.190] trace a segment of it in the fact of the unmistakably cosmic character of the spiritual life. The progressive intensifying of the Life-process has made the fact abundantly clear that Nature is not the final reality it was supposed to be by the scientific mode of the past, but that it signifies no more than a "human vista of reality." And, as we have already observed in connection with the Theory of Knowledge, the nature of that "vista" is determined by a mental process and a construction beyond Nature. Nature appears as no more than an environment when once the power of Eternal Life has appeared within the soul. An insistence on this power and _its_ capacity has raised man to a level from which he recognises the "priority of spirit" in spite of all the "palpableness of sensuous impressions." Man thus appears great as against Nature; but there is more than enough to make him humble when he views himself in the light of that truth which constitutes the Spiritual and Eternal Substance of Christianity.