Xavier Zubiri, the Spanish Christian ontologist, was born in San Sebastián. He was professor of the history of philosophy in Madrid from 1926 to 1936 and in Barcelona from 1940 to 1942, after an absence abroad during the Spanish Civil War. He then left university teaching to give well-attended "private courses" in Madrid. His influence in Spain has been out of all proportion to the scanty amount of his published work.

Zubiri has been called a Christian existentialist, and indeed that is one aspect of his effort to synthesize neo-scholastic theology with certain contemporary philosophies (those of Edmund Husserl, Martin Heidegger, and José Ortega y Gasset) and with modern science. To achieve this harmonizing of separate disciplines, Zubiri undertook studies in theology, philosophy, and natural science that could well have occupied three scholarly lives. He took a doctorate of theology in Rome and of philosophy in Madrid...