Understanding taught by experience no longer muses about universal nature, but acquires a knowledge of it by special studies. By degrees philosophy, first unconsciously and lately clearly and plainly, has taken up the problem of ascertaining the limits of understanding.
This philosophical problem first assumed the form of polemics. It became opposed to the religious dogma which represented the human mind as a small, subservient, limited and restricted emanation of the unlimited divine spirit. This terrestrial emanation was regarded as too limited to understand and find its divine source. The study of the limits of the understanding has now emancipated itself from this dogma, but not to such an extent that there is no longer any mysterious obscurity floating around the understanding and intelligence, and especially around the question whether the human mind can penetrate only into some things while others will remain in the unscrutable darkness of faith and intuition, or whether it may penetrate boldly and without hindrance into the infinity of the physical and chemical universe.
We here desire to claim as a positive outcome of philosophy that it has at last acquired the clear and exact knowledge that a socalled infinite spirit, in the religious sense, is a fantastic, unscientific conception. In the natural sense of the word, the human powers of understanding are universal and yet in spite of their universality they are, quite naturally, limited. The human understanding has its limits, why should it not? Only drop the illusion that a dark mystery is concealed beyond these limits.
The understanding is a force among others, and everything that is located alongside of other things is limited and restricted by them. We can understand everything, but we can also touch, see, hear, feel, and taste everything. We also have the power of moving about, and other qualities. One art limits another, and yet each is unlimited in its own field. The various human powers belong together and constitute together the human wealth. Be careful not to separate the power of understanding from other natural powers. In a certain sense it must be separated, because it is the special object of our study, but it must always be remembered that such a separation has only a theoretical value.
Just as our power of vision can see everything, so our understanding can grasp everything.
Let us look a little closer at this statement.
How can we see everything? Not from any single standpoint. In that sense our powers of vision are limited. But what is not visible in the distance, becomes so on approaching nearer to it. What one eye cannot see, that of others can, and what is invisible to the naked eye, is revealed by the telescope and microscope. Nevertheless the vision remains limited, even though it may be the sharpest, and armed with the best artificial means. Even if we regard all the eyes of the past and future generations of humanity as organs of the universal human vision, this vision still remains limited. Nevertheless, no one will complain about the limits of human power, because we cannot see sounds with our eyes or hear the light with our ears.
The understanding of man is limited, just as his vision is. The eye can look through a glass pane, but not through a plate of iron. Yet no one will call any eye limited, because it cannot see through a block of metal. These drastic examples are very opportune, because there are certain wise men who reflectively lay their finger on their nose and call attention to the limits of our intellect in that sense, just as if the knowledge gained on earth by scientific means were only a nominal, not a real, understanding and knowing. The human intellect is thus degraded to the position of a substitute of some "higher" intellect which is not discovered, but must be "believed" to exist in the small head of a fairy or in the large head of an almighty being above the clouds. Would any one try to make us believe that there is a great and almighty eye that can look through blocks of metal the same as through glass? The idea of a spiritual organ with an infinite understanding is just as senseless. An unlimited single thing, an unlimited single being, is impossible, unless we regard the whole world, the world without beginning and without end, the infinite world, as a unit. Within this world everything is subject to change, but nothing can go beyond its genus without losing its name and character. There are various kinds of fire, but none that does not burn, none which has not the general nature of fire. Neither is there any water without the general nature of water, nor a spirit that is elevated above the general nature of spirits. In our days of clear conceptions the tendency toward the transcendental is mere fantastic vaporing.
It is not alone unscientific, it is fantastic, to think even afar of a higher power of thought or understanding than the human one. One might as well think of a higher horse which runs with eight, sixteen, or sixteen hundred legs and carries away his rider in a higher air at a higher speed than that of the wind or the light.
It is a part of the achievements of philosophy, of correct methods of thought, of the art of thought or dialectics, to know that we must use all conceptions, without exception, in a limited, rational, commonplace way, unless we wish to stray into that region where there are mountains without valleys and where every theory of understanding loses its mind.