This book is a tribute to the life and work of J Q Chen. The contributions of Chen to nuclear and molecular physics are discussed vis-a-vis present developments in these fields. Among other subjects, the present status of microscopic theories of the interacting boson model in nuclear physics and the theory of symmetry adaptation of molecular vibrations in molecular physics are reviewed. The latter theory is particularly useful for large molecular species such as fullerenes, where icosahedral symmetry plays a fundamental role.