Ludwig Wittgenstein's book Logische- Philosophische Abhandlung (Tractatus Logico-Philosophicus) (1922) will be based upon notes he takes as a soldier in World War I and written while on a leave of absence.
Wittgenstein will believe he solves all philosophical problems in that book and as a result after the war he decides to abandon philosophy in order to teach at a grammar school in Austria.
In Tractatus Ludwig Wittgenstein argues that our world is composed of facts, pictured by thoughts, which are in turn expressed by propositions of a logically structured language. Thus, a world made up of atomic facts is described by a language of atomic propositions in a one-to-one correspondence. Everything beyond this is literally nonsense, including metaphysics, ethics, religion, and aesthetics, and this formed one of the basic doctrines of logical positivism.