... an ancient doctrine, once generallyprevalent and still by no means exploded, which I regard as the source of a great part of the obscurity hangingover some of the most important processes of ... statement and analysis not of the mere meaning of a word, nor yet of the nature of a thing,but of an idea. Thus, the proposition, "A circle is a plane figure bounded by a line all the points of ... applied to one thing, and thenextended by a series of transitions to another and another. By this process (as has been remarked by severalwriters, and illustrated with great force and clearness by...