Published in 1882, his ninth novel, 'Two on a Tower' is Hardy's most complete and daring treatment of the theme of love between characters of different classes and ages. Viviette, the married lady of the manor, is nine years older than Swithin St Cleve, the 20-year old `Adonis-astronomer', a `lad of striking beauty, scientific attainments, and cultivated bearing', the orphaned son of a curate who married the daughter of a family of farmers. The story of their love, both complex and remarkable, involves adultery and accidental polygamy. On publication some reviewers considered the novel to be immoral, and one suggested that the treatment of the Bishop of Melchester might be regarded as a `studied and gratuitous insult aimed at the Church'. This sensational tale is informed throughout by the astronomical images and reflections which were preoccupying Hardy at the time of the book's composition. This is the first critical edition of 'Two on a Tower'. Based on a study of the manuscript and Hardy's revised printed versions, it presents a text in which many variants make their appearance in print for the first time.