Heidegger's philosophy underwent significant changes through the years and has served as fertile ground for many different, and sometimes opposing views. This in-depth analysis of his major works, however, finds a fundamental thematic unity in the philosopher's effort to overcome the subjectivism of modern philosophy and to account for the ontological hierachy that it alone constitutes a foundation for everything else. The author sees this challenge to the Cartesian tradition as the key to understanding HEIdeggar's views on human beings and language, as well as their influence in the issues of identity and representation in contemporary philosophy.