Edith Wharton’s first full-length novel (1902). It is a long-ish historical novel, set in Italy in the late eighteenth century. Italy was not yet unified and was a mass of small states. The ideas of the Enlightenment and French revolutionary thinkers are spreading as far as Italian backwaters. It is the story of Odo Valsecca, the heir – later the duke – of a minor state. He reads Voltaire and meets with freethinkers. How free is a ruler to bring in reformist legislation? Can he override the all-pervasive influence of the Church? Do his subjects actually want to be reformed? Is it worth the effort? And will Duke Odo ever make a life with the woman he loves?

From http://www.enotes.com/valley-decision-salem/valley-decision:
“This … romance chronicles the rise to power of Odo Valsecca during the intellectual and political tumult which preceded the French Revolution. During his childhood and early manhood, Odo comes in close contact with all the major factions—the peasantry, the clergy, the liberal freethinkers, and the nobility—which have a vital stake in maintaining or subverting the antiquated power structure based on rigid class distinctions and superstitious religious traditions.”