His book gives an introduction to C*-algebras and their representations on Hilbert spaces. We have tried to present only what we believe are the most basicideas, as simply and concretely as we
could. So whenever it is convenient (and it usually is), Hilbert spaces become separable and C*-algebras become GCR. Thispractice probably creates an impression that nothing of value is known
about other*-algebras. Of course that is not true. But insofar as representations are con-cerned, we can point to the empirical fact that to this day no one has given aconcrete parametric
description of even the in’’ educible representations of any*-algebra which is not GCR. Indeed, there is metamathematical evidence whichstrongly suggests that no one ever will (see the
discussion at the end of Section3.4). Occasionally, when the idea behind the proof of a general theorem is exposedvery clearly in a special case, we prove only the special case and relegate
generalizations to the exercises. In effect, we have systematically eschewed the Bourbaki tradition. We have also tried to take into account the interests of a variety of readers. For example,
the multiplicity theory for normal operators is contained in Sections 2. Iand 2.2. (it would be desirable but not necessary to include Section I. 1 as well),whereas someone interested in BoreL
structures could read