The intention that directs this research consists in an attempt to provide a hermeneutic analysis of the drastic changes, which have occurred in 20th century philosophy, in identifying the new role ascribed to the subject of time and temporality within the scope of ontology. After the fundamental works of E. Husserl, M. Heidegger, P. Ricoeur, and E. Levinas, it has been understood that the traditional issue (which could be traced back to Parmenides) between being and time, between the eternal and the transient (or historical), must once again be re-examined. Time itself is recognized now as the deepest ground of ontological inquiry, which sets in motion the entire system of fundamental philosophical concepts.