In olden times, man had clairvoyant revelations and did not understand them. Today man must first understand, must exert to the utmost his intellectual power, must exert to the utmost his reason. If he so exerts it through that which lies before him in Spiritual Science, then mankind will again develop the power of receiving the Spiritual clairvoyantly.
This is certainly something that most people today wish to avoid, viz., to make use of their healthy human reason in order to understand Spiritual Science. Were it possible to avoid the use of man’s reason, it would also be possible to avoid altogether the entrance of spiritual revelations into our earthly world.
Source: Rudolf Steiner – GA 195 – The Cosmic New Year – Lecture IV – Stuttgart, 31st December 1919