  In the first of these two lectures I will discuss the rich constitution of
neutron stars as a consequence of the Pauli principle which is engaged by the
dominance of gravity over the nuclear force. Three especially interesting
phenomena are discussed in this contect--(1) a mechanism for the formation of
low-mass black holes distinct in their mass-range from the black holes formed
in the prompt collapse of an entire star, (2) a multilayered crystalline
structure consisting of confined hadronic matter embedded in a background of
deconfined quark matter (or vice versa) which occupies a many kilometer thick
inner region, and (3) a clean and pronounced signal of the formation of quark
matter in the interior of neutron stars. In the second lecture I will discuss
the strange matter hypothesis, its viability as well as its consequences for
compact stars and a new family of white dwarfs with dense nuclear matter
central regions some orders of magnuitude greater than in ordinary white
dwarfs.
