In order to understand human social activity, we must first understand human social structures. But in order to understand human social structures, we must first understand some general principles that apply to all structures. All structures are composed of dynamic arrays of opposing forces. For living creatures, we call these forces "angonisms." In the sense of their opposition, they are "antagonisms"; but in the sense of their collaboration to achieve useful goals, they are "proagonisms." The quickest way to acquire an initial understanding of "Proagonism" is to consider the muscle groups in a human arm. One of these groups extends the arm, and another group contracts the arm. These groups are "antagonists." But when they are used together to position the hand, and especially in a dynamic fashion to accomplish useful tasks, then they are also "proagonists." Understanding proagonism in a broader sense is critical to understanding human social interaction, and the human nature that underlies it. This book provides a comprehensive introduction.