Reader. Have you done?
Büchner. Yes, sir.
Reader. Is this all your proof?
Büchner. Yes, sir.
Reader. Then allow me to state that you have not shown what you promised. You have proved, indeed, that the forces of matter exist nowhere but in matter; but as every one admits this, there was no need of your proof. Your duty was to prove the universal proposition, no force without matter; and therefore you had to show that there are no other forces than the forces of matter.
Büchner. This is evident; as “force can as little exist without a substance as seeing without a visual apparatus, or thinking without an organ of thought” (p. 4).
Reader. I am afraid, doctor, that you do not speak to the point. The question is not whether a force can or cannot exist without a substance; it is, whether there is no other substance than matter. Before denying the existence of force without matter, you must [pg 443] conclusively show that all substance is matter.
Büchner. “Nothing but the changes we perceive in matter by means of our senses could ever give us any notion as to the existence of powers which we qualify by the name of forces. Any knowledge of them by other means is impossible” (p. 4).
Reader. I should be glad to know how you can infer from such a remark that all substance is matter. What you perceive in material objects proves, indeed, the existence of matter and of the forces of matter; but how does it prove the non-existence of other substances and of other forces? You, surely, imagine that our senses are our only source of knowledge, and that the supersensible, as unknowable, must be consigned to the region of dreams.
Büchner. Certainly. “We maintain that human thought and human knowledge are incapable of discovering or knowing anything supersensual. This is the necessary general result of modern investigation” (p. xli.)