The steep-roofed, three-roomed retreat is traditional for this valley and only its height above the rest and its plainness mark it out. Adam Sharr's scholarly monograph, Heidegger's Hut (MIT Press, 2006), longed for evidence that the master instructed his craftsman to build the shack in a Heideggerian way in 1922, but found none. His young wife Elfride discovered the area on a skiing holiday and when her husband fell in love with it, he chose a plot and she had the hut built with money from her parents. The result tucks neatly into the hillside and, in the local manner, causes nature no offence. Heidegger got this traditional discernment of the peasant-artisan back into philosophy, not architecture. As towns began to build over green fields and cars to clog the streets of his native Messkirch, he asked if modern life wasn't concreting over truth, rendering it no longer accessible.

What a marriage kept this man going. Just as Nietzsche saw the querulous bourgeoisie beneath Wagner's gods, Wotan and Fricke, so one can see, with the help of a lifetime of Martin's letters to his wife, a story of high-mindedness and banality. He wrote Being and Time (1927) up here in spartan conditions. When it made his career, Elfride saw her moment. No sooner established in a chair in his dear Freiburg, her husband was offered the country's top job in his subject, in Berlin. When he refused it, Elfride invited Freiburg to pay for the electrification of the hut in gratitude, which they did, in 1931. Martin's serial infidelities notwithstanding, the Heideggers were married for 60 years. She couldn't anchor him sexually, but Elfride got her own back by spending a last night with his corpse. Sitting on last year's grass, remembering the icy professional photographs of their coupledom taken up here to mark his 75th birthday, I'm struck by how he kept the creativity he brought to philosophy, giving it a value close to a work of art, so distant from his life's companion. 

Board Three insists the hut remained spartan, and that only in 1962 did it acquire a little radio to keep Heidegger in touch with the Cuban missile crisis. This influential German soulkeeper, both of whose sons were Russian prisoners of war, was addled by the Russian threat both pre- and post-war. Like Hitler, Heidegger made good use of the Bolshevik threat, conflating it with America into a mechanistic devil totally opposed to the good German spirit. Like Adorno, his Jewish shadow in exile, he thought the devil of instrumentality was crowned by the Enlightenment. When he was already at the height of his first fame, many German philosophers, including his former teacher Edmund Husserl, concluded that Heidegger wasn't doing their subject any more, but something of his own. 

"Forests store/Streams tumble/Rocks endure/Rain descends./Thresholds wait/Springs gush/Winds dwell/Blessedness feels." Heidegger's occasional poems, which he rightly preferred to call "Moments of Thought", contain little distillations of his message, like the last two lines here on Board Three: "Winde wohnen/Segen sinnt: Winds dwell/ Blessedness feels." Heidegger passionately rejected cogitation in pursuit of truth, hence blessedness as an extra and superior sense.