The theorists of scientific management seem to think that the most subtle methods are indispensable for physical measurements, but for psychological … - Hugo Münsterberg

The knowledge of nature and the mastery of nature have always belonged together.

Ethics could teach us only those purposes and ideals. If the teachers seeks insight into the means by which the aim can be reached, into the facts by which the child can be molded, his way must lead from ethics to psychology. (...) Water flows downhill, anyhow, but to bring the water uphill hydraulic forces are indeed necessary. To overcome nature and instead to prepare for a life of ideals, to inhibit personal desires and instead to learn to serve the higher purposes indeed demands most serious and most systematic efforts. It is the teachers' task to make these efforts with all his best knowledge of mind and body, of social and of cultural values.

Applied psychology can, therefore, speak the language of an exact science ill its own field, independent of economic opinions and debatable partisan interests.