How did it come about that man has now lost the understanding for the spiritual life which lies at the foundation of all physical existence? Why had this to occur?
Let us turn our gaze to our immediate surroundings. Were you able to compare man’s present environment with that which once surrounded him at every step, you would find that at that time (Steiner is referring to the culture period from about 3000 to 500 BC) man only possessed the most necessary means of subsistence; but he had, on the other hand, more comprehension for spiritual things. This comprehension for the spiritual world had to withdraw in order to give man the possibility to acquire his present dominion over the earth. Every technical and industrial progress of the present time could only be achieved through a world-conception which had become materialistic, through the fact that the spirit, the super-sensible world, withdrew. At the cost of spiritual contemplation man gained, in the course of the last centuries, his rule over the physical world. It is a primordial, eternal law of humanity that capacities acquired in one sphere, can only be gained by the withdrawal of others upon another sphere. For instance, man could never have called into life the possibilities of travel and communication had other capacities not withdrawn. The sense for spiritual things had to withdraw, in order that everything which now surrounds us might arise. All that once filled the human soul had to withdraw, to render possible the conquest of the physical world.
Thus we see that around the 16th century men lost the vision of the spiritual world, and we see how the materialistic conception took hold of humanity. Those who believe that they themselves do not live in the very midst of such materialism are greatly mistaken.
It is not the task of spiritual science to deny or renounce things; it does not intend to criticise the bad world of to-day; but it wishes to indicate the necessity of man’s descent into matter. The great horizon of spiritual life had to withdraw from humanity while this descent took place, and this explains why man lost the old way of comprehending spiritual things. The truths exist in their old, earlier forms. Spiritual science can show how those truths can be rendered accessible to modern men. This is its chief aim. Consequently anthroposophy is merely the instrument whereby the deepest truths can be rendered accessible to the modern human spirit, in order that they may be grasped in their full depth.
Source: Rudolf Steiner – GA 100 – Theosophy and Rosicrucianism: Lecture I: Theosophy and Rosicrucianism – Kassel, 16th June 1907