Wittgenstein observes that certain imaginative pictures can seem so obvious, so self-evident, that they "force" themselves on us. The picture that "held us captive" here was a conception of the isolated ego, the contents of whose mind are transparent to its knowing, while contact with the world is mediated by some kind of "representation." This mind-world dualism, which pictures a contrast between "inner" and "outer," has exercised a "powerful...