However much a clairvoyant may be able to investigate and see in the spiritual world, what he sees is of no value to him and to others so long as he is unable to bring it down into the ordinary sphere of men, and to express it in thought that can be grasped by sound logic and a natural feeling for truth. The clairvoyant must in fact first understand the matter himself if it is to be of any use to him. Its value begins where the possibility of logical proof begins. […] Picture to yourselves a man who has perhaps made quite exceptional discoveries in the spiritual world through purely clairvoyant observation, but who has neglected to clothe these observations in language suited to the ordinary sense of truth of any age. Do you know what would happen to him? All his discoveries would be wiped out after death! Just as much of value would remain as it was possible for him to translate or formulate into any language that corresponded to a sound sense for truth.
It is certainly of the greatest importance that there should be clairvoyants capable of bringing over communications from the spiritual world and handing them on to others. This brings blessing to our day, for our age has need of wisdom and cannot advance unless it gets it. Such communications are necessary to the culture of the present time. If not recognised to-day, in fifty or a hundred years it will be the universal conviction of all mankind that culture cannot advance but must perish unless convinced of spiritual wisdom.
Source: Rudolf Steiner – GA 124 – The Gospel According to St. Mark – Berlin, 17th October 1910