And it must be sought by methods quite different from those by which it has been sought hitherto. To some extent Kant attempted to describe how he represented to himself the meaning hidden beneath the words: 'Space and time are subjective forms of perception.' He even gave an object-lesson, saying that perhaps there are beings who perceive the world otherwise than under the forms of space and time: which means that for such beings there is no change. All that we perceive by a succession of changes, they perceive at once. To them Julius Caesar is still alive, though he is dead; to them the twenty-fifth century A.D., which none of us will live to see, and the twenty-fifth century B.C., which we reconstruct with such difficulty from the fragmentary traces of the past which have accidentally been preserved to us, the remote North Pole, and even the stars which we cannot see through the telescope--all are as accessible to them as to us the events which are taking place before our eyes. Nevertheless Kant, in spite of all temptation to acquire the knowledge to which such beings have access, notwithstanding his profound conviction of the truth of his discovery, did nothing to dispel the charm of forms of perception and categories of the reason, or to tear the blinkers from his eyes and see all the depth of the mysterious reality hitherto hidden from us. He does not even give a little circumstantial explanation why he considered such a task impracticable, and he confines himself to the dogmatic assertion that man cannot conceive a reality beyond space and time. Why? It is a question of immense importance. Compared with it all the problems of _The Critique of Pure Reason_ are secondary. How is mathematics possible, how are natural sciences possible?--these are not even questions at all compared to the question whether it is possible to free ourselves from conventional human knowledge in order to attain the ultimate, all-embracing truth.