What do we need to know in order to read Ulysses properly? An intimidating question, perhaps, by which to introduce a notoriously intimidating book. But reading of any kind, whether of Ulysses or of Goldilocks and the Three Bears, never takes place in an entirely blank or virgin mind. Other discourses are always implicated. Unlike Goldilocks, however, Ulysses poses the question of prior knowledge with some urgency because it can make us feel so unknowing, and with such devastating speed, and because sometimes a small bit of information available outside the novel, or inside it but hundreds of pages further on, can just as quickly unravel pages of confusion. One of the questions raised by such difficulties is central to literary studies in general: what is inside the literary object? What lies outside it? Can the border lines be drawn with any certainty? My intention is not to proclaim boundaries, nor to choose between right or proper readings and wrong ones, but only to indicate the kinds of knowledge that Ulysses seems to require. My survey is brief, and hardly exhaustive. It is a preface to the major focus of this essay: what is Ulysses 'about', and how can it be read?