THE article by Mrs. S. Neville Rolfe in NATURE of January 24, p. 90, calls for comment and support. Does it occur to the average man that, except at some schools, everything taught is factual, with definite conclusions? For example, history, geography, grammar, mathematics, physics and chemistry all produce definite results. But when we enter the world in which we live, we are emerging into a world of living and thinking beings. The facts can be ascertained, though often with much difficulty, but the conclusions are too often matters of probability.