I can’t quite work this one out.
From Dorothy Dunnett – Pawn in Frankincense:

From NC:
1. Where did Roksolana come from, the famous wife of Sultan Suleiman the Magnificent
2. Roksolana achieved the execution of Ibrahim Pasha in order to protect her native Italy from the Turkish invasion. Thus she saved the Vatican and the Reformation.
3. “Pargal Damat Ibrahim” means “decorated with flowers and horse Abraham.” In the XVI century in Turkey, as in Russia, the second man after the emperor was called the stable
4. The mosque of St. Sophia in Istanbul was built by Roksolana and served as the original burial vault of Suleiman and Roksolana
5. Saint Catherine of Siena – a reflection of Roksolana
5.2. When Catherine of Siena lived actually
5.3. Arrogant Epistles of Catherine to the Pope of Siena and European Sirs
5.4. The mystical betrothal and the exchange of hearts of Catherine of Siena with the king of heaven – Christ symbolize the betrothal of Roksolana with the king of the earth – Suleiman
5.5. Catherine of Siena, like Roksolana, was forced to leave her hometown to get into the circle of rulers of the world and the church
5.6. The symbolic image of the execution of Ibrahim: the triumphant Catherine of Siena raises the severed head of a man over a crowd of Romans
5.7. “Avignon captivity” of the popes was not in the XIV, but in the XVI century