The roots of Heidegger's thinking lie deep in the Western philosophical tradition. Yet that thinking is unique in many of its aspects, in its language, and in its literary expression. In the development of this thought Heidegger has been taught chiefly by the Greeks, by German idealism, by phenomenology, and by the scholastic theological tradition. In him these and other elements have been fused by his genius of sensitivity and intellect into a very individual philosophical expression.