sentences:  A single body of many particles, as in a gas, is not an "ensemble" of particles in the sense of the "ensemble interpretation", although a repeated preparation and observation of many copies of one and the same kind of body of particles may constitute an "ensemble" of systems, each system being a body of many particles.The ensemble is not in principle confined to such a laboratory paradigm, but may be a natural system conceived of as occurring repeatedly in nature; it is not quite clear whether or how this might be realized.The members of the ensemble are said to be in the same state, and this defines the term 'state'.