This volume contains contributions by former students and collaborators of Haim Brezis given in honor of his 60th anniversary at a conference in Gaeta. H. Brezis has made significant contributions in the fields of partial differential equations and functional analysis. He is an inspiring teacher and counselor of many mathematicians in the front ranks. The collection of papers presented here grew out from his deep insight of analysis. In addition it reflects Brezis's elegant way of creative thinking.