Who wrote the philosophical treatise Being and Time?

Heidegger, in 1927, and it is unfinished - the published book is roughly a third of the announced plan, and the rest never appeared. It asks what it means for anything to be at all, a question he claimed Western philosophy had been ignoring since the Greeks by studying particular things instead.

Reading it is a fight, partly by design. He held that ordinary philosophical vocabulary already smuggled in the assumptions he wanted to dismantle, so he built his own out of hyphenated German compounds - being-in-the-world, ready-to-hand, thrownness - which translators have argued about ever since. The famous example is simple enough: a hammer in use disappears into the task, and only becomes an object you notice when it breaks.

He joined the Nazi party in 1933, became rector of Freiburg, and gave a notorious inaugural address; he never publicly recanted, and the private notebooks published from 2014 contain explicit antisemitism, closing off the defence that it was opportunism. His influence is nonetheless enormous - on Sartre, Arendt, Levinas, Derrida - and several of those thinkers were Jewish, some of them his students, which is a tangle the field has not resolved and mostly declines to tidy.