Although the biography as a historiographical form is and has been widely used and widespread, its scientific value has been mostly unrecognized. In particular, in the history of philosophy, in line with the modern split between life and thought, the latter has been considered to be substantially independent of life. The work by Wilhelm Dilthey (1833-1911) offers a different approach to this question. His research into the relationship between life and thought materialized in two biographies: Leben Schleiermachers (1870) and Die Jugendgeschichte Hegels (1905). Dilthey focused on the writing of biographies throughout his whole intellectual journey. In fact, some of the key topics of his philosophy (criticism to the trascendental approach, centrality of the individual and the psychology) emerge from his work on biographies. The attempt to establish a scientific biography is an essential part of his critique of historical reason.