Many problems in operator theory lead to the consideration ofoperator equa- tions, either directly or via some reformulation. More often than not, how- ever, the underlying space is too 'small' to contain solutions of these equa- tions and thus it has to be 'enlarged' in some way. The Berberian-Quigley enlargement of a Banach space, which allows one to convert approximate into genuine eigenvectors, serves as a classical example. In the theory of operator algebras, a C*-algebra A that turns out to be small in this sense tradition- ally is enlarged to its (universal) enveloping von Neumann...