appropriate term for it? The material and the spiritual are both two species of the same genus. How are we to designate the species, how the genus? For the sake of complete clearness, we require three different names, one for each species and a common general name. But since we are much less concerned about the name than about the understanding of these facts which cannot be well explained without terms, we do not insist dogmatically on calling the understanding material. It is sufficient to point out that the function of the heart and of the brain both belong to the same class, no matter whether this class be called material, real, physical, or what not. So long as language has not established a definite meaning for these terms, all of them serve equally well and are equally deceptive. The positive outcome of philosophy which culminates in placing the theory of understanding in the same class with all other theories, cannot be easily demonstrated on account of a natural confusion of thought which arises from an equally natural confusion of language. In the special department of handicraft as well as in that of scientific brain work the terminology is well systematized, while in the general affairs of life and science there is a confusion which is as great in the matter of conceptions as in that of applying the terms by which those awkward conceptions are expressed. Wherever understanding is clear, there the language is also clear. The man who does not understand shoemaking does not understand its terminology. This is not saying that the understanding of a trade and the understanding of its terminology are identical, but only indicating their actual connection. If the reader has had a glimpse of the enormity of the work of more than two thousand years of philosophy in order to state what little we know today of its achievement in the science of understanding, he will not be very much surprised at the difficulties we here meet with in finding terms for its demonstration. The function of the brain is as material as that of the heart. The heart and its function are two things, but they are dependent one upon the other so that one cannot exist without the other. The function may partly be felt. We feel the heart beating, the brain working. The working of the heart may even be felt by touch, which is not the case with the working of the brain. But it would be a mistake to imagine that our knowledge of the function of the heart is exhausted by our perception of it through the touch. Once we have overcome the habit of making exaggerated distinctions between things, and have learned to consider the differences of things as well as their interconnection, we can easily understand that the science of the function of the heart is an infinite science which is connected with all others. The heart cannot work without the blood, the blood cannot exist without food, and this is connected with the air, the plants, the animals, the sun, and the moon.