 After completing the Aufbau first draft in late 1925, along these new lines, Carnap left for Vienna, where he became a lecturer [Privatdozent] and submitted the Aufbau manuscript to Moritz Schlick as his Habilitationsschrift. He immediately became an active participant in Schlick’s weekly Circle, which was embarking just then on yet another careful re-reading of Wittgenstein’s Tractatus. This group would soon (due to Otto Neurath’s effective propaganda) become known to the world as the “Vienna Circle”, the fount of a new (anti-)philosophy known as “logical positivism”—a term Carnap never liked. 