After serving in the Austro-Hungarian Army during World War One the philosopher Ludwig Wittgenstein completed his seminal work- the Tractatus Logico-Philosophicus whilst on leave at his familys summer house in Vienna in August 1918. Setting out to map out the relationship between logic, thought and the world the Tractus delivers its arguements as a series of declarations of self-evident truths: 1. The world is all that is the case. 2. What is the case (a fact) is the existence of states of affairs. 3.A logical picture of facts is a thought. 4. thought is a proposition with a sense. And so on; the totality of facts we learn contains the subject matter of the physical sciences. Concepts outside of logical correalation in 'Whereof we cannot speak, thereof one must be silent' In this category Wittgenstein consigned theology, ethics and religon. Or that's one view in any case- Only propositions with actual logical content that was mapped onto the logical form of the world could be meaningful. In later life Wittgenstein revisited the propositions in the Tractatus and dissected them in a series of writings that became the posthumously published 'Philosophical Investigations.