Process and Reality, Whitehead's magnum opus, is one of the major philosophical works of the modern world, and an extensive body of secondary literature has developed around it. Yet surely no significant philosophical book has appeared in the last two centuries in nearly so deplorable a condition as has this one, with its many hundreds of errors and with over three hundred discrepancies between the American (Macmillan) and the English (Cambridge) editions, which appeared in different formats with divergent paginations. The work itself is highly technical and far from easy to understand, and in many passages the errors in those editions were such as to compound the difficulties. The need for a corrected edition has been keenly felt for many decades