In his foreword to the 1977 edition of this "encyclopedia," quoted in the current preface, Jean Piaget tells of an encounter with a Scandinavian colleague who says: "You have certainly never read anything of mine, and never will. As far as I am concerned, I have not read anything of yours, and this will not change. We should find devoted young collaborators who would inform each of us of the works of the other." This interchange occurred in 1954 between two developmental psychologists with "similarities" in their works. Even then, in a field relatively well defined, two experts would be so overwhelmed—already drunk and satisfied—with the publications of scholarly papers, theses, and books, that they couldn't have time to read each other's work, never mind mastering the whole psychological field.