Liebig, who is especially fond of straying from his inductive science into the field of speculative thought, says in an idealist sense: "Force cannot be seen, we cannot grasp it with our hands; in order to understand its nature and peculiarities, we must investigate its effects." And if a materialist replies to him: "Matter is force, force is matter, no matter without force, no force without matter," it is plain that either has determined this relation only negatively. In certain shows, the clown is asked by the manager: "Clown, where have you been?" "With the others," answers the clown. "And where were the others?"--"With me." In this case we have two answers with the same content, in the other we have two camps which quarrel with different words about an indisputable fact. And this dispute is so much more ridiculous because it is taken so seriously. If the idealist makes a distinction between matter and force, he does not mean to deny that the real phenomenon of force is inseparably linked with matter. And if the materialist claims that there is no matter without force and no force without matter, he does not mean to deny that matter and force are different, as his opponent claims. The dispute exists for a good reason and has its object, but this object is not revealed in the dispute. It is instinctively kept under cover by both parties, so that they may not be in a position where they would have to acknowledge their own ignorance. Each wants to prove to the other that the other's explanations are inadequate, and both demonstrate this sufficiently. Buechner admits in the closing statements of his "Matter and Force" that the empirical material is insufficient to permit of definite answers to transcendental questions, and that therefore no positive answer can be given to them. And he furthermore says that the empirical material "is fully sufficient to answer them negatively and to do away with hypothesis." This is saying in so many words that the science of the materialist is adequate for the proof that his opponent knows nothing.