Lecture I

In medieval Scholasticism all of man's thinking, all of his notional activity, was determined by the view that one could explain the broad realms of nature in terms of certain concepts but that one had to draw the line upon reaching the super-sensible. The super-sensible had to be the object of revelation. They felt that man should stand in a relation to the super-sensible in such a way that he would not even wish to penetrate it with the same concepts he formed concerning the realms of nature and external human existence. A limit was set to knowledge on the side of the super-sensible, and it was strongly emphasized that such a limit had to exist, that it simply lay within human nature and the order of the universe that such a limit be recognized. This placement of a limit to knowledge was then renewed from an entirely different side by thinkers and researchers such as du Bois-Reymond. They were no longer Schoolmen, no longer theologians, but just as the medieval theologian, proceeding according to his own mode of thinking, had set a limit to knowledge at the super-sensible, so these thinkers and researchers set a limit at the sensible. The limit was meant to apply above all to the realm of external sensory data.