ABSTRACT
IN Chapters 111 and IV we have developed the general principles of the quantum dynamics of a single particle. We must now pass on to study the dynamics of systems composed of several particles. The two main problems are the relation of such a system, considered aa a whole, to the particles, or sub-systems, of which it is composed ; and the interaction of the sub-systems among themselves, with its efIect on the historical development of the system as a whole.
