By a remarkable coincidence, the two most notable contributors to cosmology in the middle and late eighteenth century had each learned his astronomy from the popular English textbooks of his day. The achievements of Thomas Wright of Durham and William Herschel were in stark contrast: Wright, an eccentric steeped in religious symbolism, was led to ask speculative questions about the location of Heaven and Hell and about the large-scale distribution of the stars which contemporary astronomers had neglected; Herschel, arguably the greatest observer of all time, constructed monster telescopes and turned them like long-range artillery against the problems of the construction of the heavens.¹ But the two men had in common their limited formal education, their insatiable curiosity and access to the popular English astronomy books of the time. What, then, was to be learned from such books, and how successfully did they define the frontiers of knowledge of the "fixed" stars and of the universe in the large?