Ludwig Wittgenstein is considered one of the greatest philosophers of the 20th century. While much of the notes written during his most productive years were destroyed, several remain; is comprised of a particular set of personal notes from the period during which he wrote Tractatus Logico-Philosophicus, detailing his thoughts and ideas during a critical period in his life. Published with Wittgenstein's native German parallel to the English translation, this new second edition includes new notes and photographs of the original work.