The soul life of man, as well, is entirely accommodated to space and time. If you enter a world to which you are not adapted, the lack of adaptation implies sensations of pain and suffering; so that the first entrance into the spiritual world is not won without the vanquishing of pain and suffering. […]
There are indeed few people today who have sufficient inner courage to venture themselves, as it were, into the bottomless and timeless in actual experience. Certain people, however, are bound by their destiny to cross over the threshold; and without the wisdom which can be brought over from beyond the threshold no further progress is possible.
Source: Rudolf Steiner – GA 194 – The Mysteries of Light, of Space, and of the Earth: Lecture III: Historical Occurrences of the Last Century – Dornach, December 14, 1919