Nature is not experienced in its completeness if one does not ascend from what is sense-perceptible to the spirit.

 

Rudolf Steiner, from Chapter 31 of his autobiography:  "And look especially at the way my Theosophy is presented. With every step that is taken in this book, spiritual vision stands there in the background. Nothing is said that does not stem from this spiritual vision. But as the steps are being taken, it is first of all, at the beginning of the book, natural-scientific ideas in which this vision cloaks itself; then this vision, in ascending into the higher worlds, must become ever more active in freely forming pictures of the spiritual world. But these pictures grow from what is natural-scientific like the blossom of a plant grows from its stem and leaves. Just as the plant is not beheld in its completeness if one views only its stem and leaves, so nature is not experienced in its completeness if one does not ascend from what is sense-perceptible to the spirit."

Source: https://rsarchive.org/Articles/GA030/English/MP1989/IndPhi_appendixII.html