The book concerns the publication of 176 genealogical trees belonging to the Catholic Bishopric of Santorini. They were created in the 19th century by priests of the island's Catholic Bishopric with the purpose of managing the "sacred obligations", that is, the legacies left by the devout faithful of the island to their descendants. Originals and copies or drafts bear seals, signatures, and coats of arms of the most well-known families who lived on the island and in the Aegean in general. In their margins, there are wills that surround names found in the trees. The book is accompanied by summaries in Italian and English, indexes, color facsimiles of all the documents, and a special photographic insert dedicated to the Spartali family. A second photographic insert showcases Santorini as seen by European travelers from the 15th to the 18th century. Additionally, the publication is accompanied by a digital disc, which contains a 990-page file with transcriptions of the genealogical trees, as well as another file with facsimiles of the documents themselves, so that the reader can view them on their digital medium's screen.