We must make use of terms and sometimes of provisional terms. But we must guard against such terms and the mental danger of excessive intension they carry with them. The child takes a stick and says it is a sword and does not forget, he takes a shadow under the bed and says it is a bear and he half forgets. The man takes a set of emotions and says it is a God, and he gets excited and propagandist and does forget; he is involved in disputes and confusions with the old gods of wood and stone, and presently he is making his God a Great White Throne and fitting him up with a mystical family. Essentially we have to train our minds to think anew, if we are to think beyond the purposes for which the mind seems to have been evolved. We have to disabuse ourselves from the superstition of the binding nature of definitions and the exactness of logic. We have to cure ourselves of the natural tricks of common thought and argument. You know the way of it, how effective and foolish it is; the quotation of the exact statement of which every jot and tittle must be maintained, the challenge to be consistent, the deadlock between your terms and mine. More and more as I grow older and more settled in my views am I bored by common argument, bored not because I am ceasing to be interested in the things argued about, but because I see more and more clearly the futility of the methods pursued. How then are we to think and argue and what truth may we attain? Is not the method of the scientific investigator a valid one, and is there not truth to the world of fact in scientific laws? Decidedly there is. And the continual revision and testing against fact that these laws get is constantly approximating them more and more nearly to a trustworthy statement of fact. Nevertheless they are never true in that dogmatic degree in which they seem true to the unphilosophical student of science. Accepting as I do the validity of nearly all the general propositions of modern science, I have constantly to bear in mind that about them too clings the error of excessive claims to precision. The man trained solely in science falls easily into a superstitious attitude; he is overdone with classification. He believes in the possibility of exact knowledge everywhere. What is not exact he declares is not knowledge. He believes in specialists and experts in all fields. I dispute this universal range of possible scientific precision. There is, I allege, a not too clearly recognised order in the sciences which forms the gist of my case against this scientific pretension. There is a gradation in the importance of the individual instance as one passes from mechanics and physics and chemistry through the biological sciences to economics and sociology, a gradation whose correlations and implications have not yet received adequate recognition, and which does profoundly affect the method of study and research in each science.