One of the odder facts about Nicolas Copernicus is that his great work De revolutionibus remained unpublished until he was on his deathbed. Certainly the dutiful Polish Canon knew that accusations of heresy would greet his sun-centered cosmology. But in this striking presentation, the deeper reason for the delay is a neurotic uncertainty--or ruined passion for certainty--arising from the astronomer's relationship with his sadistic, intensely loved and hated brother Andreas. Andreas' systematic destructiveness thrusts Nicolas into frozen isolation and increasingly poisoned mistrust of any final "truth." Indeed, no test of his theory was technologically possible during his own lifetime; Banville's lonely Canon Koppernigk comes to see the heliocentric-geocentric question as perhaps only a rivalry of sterile illusions--points of light in ambiguous motion. And thus he spends decade after methodical decade going about his duties in the see of Ermland in war-torn Baltic Poland. The final decision to publish is brilliantly presented by Banville through the eyes of a Nabokovian mad narrator--a former disciple lost in his own delusions. Elsewhere the book is less successful; a lifetime of barren doubts is not easy to project as imaginative drama. Banville's deliberately low-keyed and reticent style can sink into arid exposition; how much more Marguerite Yourcenar accomplishes in The Abyss (p. 424). This smaller achievement rarely commands our wonder, but at its best it does have a sort of poised conscientiousness which commands liking and respect.