At the height of World War Two, the most influential philosopher of the twentieth century delivered a series of lectures on a poem about the Danube river, by one of Germany's greatest poets. The philosopher was Martin Heidegger, who in 1927 achieved worldwide fame with his magnum opus, Being and Time. Heidegger embraced the National Socialist 'revolution' in 1933, becoming rector of Freiburg University. His inaugural address culminated in 'Heil Hitler!' After clashing with the Nazi bureaucracy, he resigned the rectorate in 1934. Nine years later, as the tide of the war was turning against Germany, Heidegger spent the summer semester lecturing on the poetry of Friedrich Hölderlin. He focused on a poem about the Danube known as 'The Ister.' Rather than an esoteric retreat into the world of poetry, Heidegger's lectures were a direct confrontation with the political, cultural and military chaos facing Germany and the world in 1942, a time the philosopher characterized in his lectures as "the stellar hour of our commencement." However controversial Heidegger continues to be, his thought remains alive in the work of some of the most remarkable thinkers and artists working today.