II. The Logic of Thought and the Logic of Reality

Mach proceeded in a rather more popular fashion, but his idea is the same as that of Avenarius. He says: there are not subjective ideas on the one hand, and objective things on the other. All that exists in reality is the content of our sensations. I, to myself, am only a content of sensation, the table outside me is a content of sensation, my brain is a content of sensation. Everything is a content of sensation, and the concepts men make for themselves only exist for the purpose of economy. It was about the year 1881; I was present at a meeting of the Academy of Sciences in Vienna where Mach gave his lecture on the Economy of Thought, entitled: “Thought as a Principle of the Least Action.” I must say, it made quite a terrible impression upon me, who was then a mere boy, at the very beginning of the twenties. It made a terrible impression on me when I saw that there were men so radical in their ideas, without an inkling of the fact that on the paths of thought there enters into the human soul the first beginning of a manifestation of the super-sensible, the spiritual. Here was a man who denied the reality of concepts to such an extent as to see in them the mere results of a mental activity bent upon economy.