If we take Heidegger's ontology to be a philosophy of history, then, for Husserl, the problem of history is only one among the three major directions of his thoughts. After Husserl met Dilthey in 1905, he more and more attended to the problem of history and reflected upon the longitudinal intentionality of time-genesis-history. His basic idea is to grasp the condition of possibility of history by means of an eidetic intuition upon the longitudinal intentionality. However, because Husserl never explicates his thoughts on history in his published works, he is often regarded as a “non-historical” philosopher. In fact, like Dilthey, Husserl purports to combine historical enlightenment with critique of knowledge. It is hence Dilthey-Yorck, Husserl, Heidegger and Gadamer who established together the most important tradition of history of philosophy in the twentieth century, namely, phenomenological-ontological philosophy of history.