Looking at pictures is a diverse and personal experience. Some find in them an emotional impact, some an esthetic delight, and still others study them primarily for the information they may contain. And this, of course, varies also with the nature of the picture involved. Some score heavily on all three fronts while other touch only one or perhaps fail in all aspects with at least some of their viewers. Thus a book dealing primarily with pictures must of necessity be a very personal thing. This is certainly the case with the present volume.--Preface.