Even before going to Vienna in the autumn of 1933 I had read some works by Schlick, Reichenbach, and Carnap and made an effort to keep up with the issues of the periodical Erkenntnis. I had written a short book on the "New Philosophy of Nature in Germany", in which I was at pains to signalize how important the trend was they had started. This trend was almost unknown in Italy, and at the time, I myself had not fully understood its most novel and original tenets.