To gain knowledge of general principles by way of abstract exposition is a possible but not an expeditious course. It seems wiser to approach them with a large but well-defined project in view, a project which calls for continued and varied application of the principles to be studied, and which may serve at once as goal and as illustration.

The Nature of Physical Reality: A Philosophy of Modern Physics, Chapter I (p. 1), McGraw-Hill Book Co., Inc. 1950