This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part examines some integrative concepts of Wilfred Bion’s theory. It elucidates key concepts in Bion’s thinking, such as container and contained, the selected fact, and the caesura. The part deals with processes of the inner world of the individual person, and the way he interprets and understands the reality in which he is living. In fact the person, group, and society are inextricably interlaced. The part discusses the small group and its unconscious processes. Although Bion’s paradigms have greatly influenced psychoanalytic conceptions of small group processes, this section integrates the thinking of Bion with that of Melanie Klein. Bion needed great courage to formulate the three universal assumptions outlining the life of every group in such simple terms. Their clarity and simplicity made them into paradigms, serving to advance the study of groups by light-years.