Book excerpt: Full facsimile of the original edition, not reproduced with Optical Recognition software. This work attempted to fill the need for a presentation of real, modern, scientific psychology so that it could be understood by the average American enlisted man during World War II. It was intended so that every soldier who reads it should understand and use more effectively those most complicated "instrumentalities of war," that is, his own human reactions. Many of the preeminent psychologists of the era contributed chapters. Profusely illustrated.