Monopole, quadrupole and pairing: a shell model view

6 pages 4 figures revtex contrib. to Conf. on achievements and perspectives in nucl. str. Crete July 1999, to appear in Physica ScriptaThe three main contributions to the nuclear Hamiltonian - monopole, quadrupole and pairing - are analyzed in a shell model context. The first has to be treated phenomenologically, while the other two can be reliably extracted from the realistic interactions. Due to simple scaling properties, the realistic quadrupole and pairing interactions eliminate the tendency to collapse of their conventional counterparts, while retaining their basic simplicity