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. It is true that all things, including our understanding, may be improved. Everything develops, why should not our intellects do so? At the same time we may know _a priori_ that our intellect must remain limited, of course not limited in the sense of the dunce, just as our eyes will never become so sharp that they can see through metal blocks. Every individual has its limited brain, but humanity, so the positive achievements of philosophy have shown, has an intellect of as universal a power as any that can be imagined, required, or found, in heaven or on earth.