In order to know how to relate these pictures (of the spiritual world) to the spiritual reality they represent, we have to apply to them the exact thought processes we have acquired as modern human beings. We really have to think within this world of pictures in the very way we have learnt to think in the ordinary physical world. Every thoughtless glance is damaging to modern initiation. All the healthy ways of thinking we have developed as modern human beings must be brought to bear on higher knowledge. Just as we can find our way about the ordinary physical world if we can think properly, so can we only find our way about in the world of the spirit — which we enter through modern initiation — if we are able to penetrate with the thinking we have gained here in the physical world into all the knowledge we attain through Imagination, Inspiration, Intuition.
Source: Rudolf Steiner – GA 210 – Old and New Methods of Initiation: Lecture 7 – Dornach, 12th February 1922