From the back cover:
The Ambassadors of the Unconquered Sun
Travelers, diplomats and spies, the Eclipse Castes of the Solar Exalted are the emissaries of the Solar Tribe. Yet, these far-ranging wayfarers are more than just negotiators and merchants. With its understanding of human nature and its skills at the bargaining table, the Eclipse Caste serves as the key advisor to the more militant castes.
The Envoys of Righteousness
Caste Book: Eclipse is fifth Caste Book for Exalted—books detailing the different castes of the Solar Exalted. Within its pages are all of the secrets of the Eclipse Castes, from the perfect and unbreakable oath they can administer to their fragmentary memories of the First Age to the mastery of the social process they wield. This book also contains new magical powers, rules, and artifacts that Eclipse Caste characters will need to carry out their diplomatic missions.