This is the most substantial piece of writing I have read in the past decade. The ambition of it is astounding: to Understand Understanding, what happens when we understand something, and in turn what it is that we understand on those occasions when we do so. The author is attempting to do in the 20th Century what Aquinas tried to do in his century, taking into account all that has happened in mathematics, philosophy, the physical and social sciences in the intervening centuries. The implications for epistemology and metaphysics, for ethics (including politics), for both "natural" and "revealed" theology are outlined in detail. Although it's hard to think of a more universally pertinent topic than "human understanding", few actual humans would think of the questions addressed in this volume; even fewer would attempt to answer them, and very few would make such an impressive performance. Bernard Lonergan, a Jesuit with advanced study in philosophy and mathematics as well as theology, was one of the very few. I plan to read this text through at least once more within the next few months. Whether or not you think he succeeded in his ambition, reading this text is one of the most exhilarating intellectual experiences you are likely to encounter. I cannot think of a text with more "thoughts per page" than this one. If, like me, you tend to "skim" most texts presuming that most of the ink is simply fluff, be warned: there is NO fluff here. However closely you read Insight, there is meaning to be harvested. Of course this may not be your taste in books, but I will venture that if you do devote the time this text requires you will never regret having invested it here. It will be time spent with one of the Great Teachers.