Tractatus Logico-Philosophicus (Revised)
Perhaps the most important work of philosophy written in the 20th century, Tractatus Logico-Philosophicus was the only philosophical work that Ludwig Wittgenstein published during his lifetime. Written in short, carefully numbered paragraphs of extreme brilliance, it captured the imagination of a generation of philosophers. For Wittgenstein, logic was something we use to conquer a reality which is in itself both elusive and unobtainable. He famously summarized the book in the following words: What can be said at all can be said clearly; and what we cannot talk about we must pass over in silence. The work is prefaced by Bertrand Russell's original introduction to the first English edition.