This book is a work of philosophy concerning how we should think about social life. Whereas social science has traditionally been a study of social physics (a study of material individuals that interact in time and space) it must become a study of social life (a study of the vital forms and feelings of an inherently social species). Working upon an image of life as a branching tree, the book makes a case for a concept of social life founded upon a study of three fundamental dynamics: love, play, and individuation.