sion is, of course, impossible. A few broad areas may, however, be roughly marked as those in which the method of sociology has fruitful application. Let me seek some illustrations of its workings. I will look for them first of all in the field of constitutional law, where the primacy of this method is, I think, undoubted, then in certain branches of private law where public policy, having created rules, must have like capacity to alter them, and finally in other fields where the method, though less insistent and pervasive, stands ever in the background, and emerges to the front when technicality or logic or tradition may seem to press their claims unduly.
I speak first of the constitution, and in particular of the great immunities with which it surrounds the individual. No one shall be deprived of liberty without due process of law. Here is a concept of the greatest generality. Yet it is put before the courts en bloc. Liberty is not defined. Its limits are not mapped and charted. How shall they be known? Does liberty mean the
