Bernard Lonergan (1904-1984) was a noted Canadian philosopher and theologian. He devoted his life to articulating a generalized method of inquiry and its implications, not only for the human and natural sciences, but also for a better world and a higher quality of human life. His own clear vision showed him the need to overcome the terrible fragmentation of knowledge and life in our time. The struggle to achieve an integrated view is the theme that unified the body of his work. In the history of that struggle, Understanding and Being plays a central role. Published a year after his profound and complex Insight, it is the edited transcription of some thirty hours of Lonergan's lectures on that seminal book. Understanding and Being serves as a guide to the very challenging terrain of Insight, or, as one commentator put it, if Insight is the Everest in the range of Lonergan's works, Understanding and Being is the approach through rolling foothills. This edition, the second, incorporates more of the historical setting in the text and adds a wealth of explanatory notes, as well as previously unedited discussions that followed the lectures.