Of course, even to-day a consistent positivist could call the universal constants mere inventions which have proved to be uncommonly useful in making possible an accurate and complete de- scription of the most diversified results of meas- urements, But hardly any real physicist would take such an assertion seriously. The universal constants were not invented for reasons of practi> cal convenience, but have forced themselves upon, us irresistibly because of the agreement between the results of all relevant measurements, and— this is the essential thing—we know quite well in advance that all future measurements will lead to these selisame constants. ‘To sum it all up, we can say that physical science demands that we admit the existence of a real world independent from us, a world which ‘we can however never recognize directly but can apprehend only through the medium of our sense experiences and of the measurements mediated by them. If-we pursue this principle further, our outlook ‘on the world takes a different form, ‘The subject of the observation, the observing Ego, loses its position at the focus of thought and is relegated