One of the most famous rulers of Sweden was Queen Kristina (often spelling in the English way, "Christina"). She not only governed Sweden during an era that was historically important, but she also interacted with some of the most important people of her time.
In 1646, she began to write letters to Rene Descartes, the French thinker who almost single-handedly began modern rationalist philosophy. They discuss love, ethics, God, and creation; she is interested in his Roman Catholic views: she is, like 99% of Swedes, Lutheran.
In 1648, she will play a leading role in the negotiations which bring an end to the Thirty Years War, and bring peace to Europe. The negotiations are held in a church in Germany. Some people praise her for bringing peace; others will condemn her, because the war ended badly for Sweden. Until this time, Sweden had been very powerful in European politics and economics; after this time, Sweden will be less significant.
In 1650, Queen Christina invites Descartes to Stockholm, so that they can discuss philosophy together. She wants to meet with him every morning at 5:00 am in a poorly-heated room in her palace; in order to do this, he must arise at 3:30 am, because the house where is he staying is more than an hour's journey away. He contract pneumonia and dies.
After a series of secret letters to Jesuits, discussing the Roman Catholic faith, she abdicates in 1654, and travels to Rome, where she officially converts to Roman Catholocism and meets with the pope in 1655. She will remain active in European politics, travelling through France, Sweden, Italy, and elsewhere. She will continue her interest in philosophy, and the impact of philosophy on astronomy, carrying with her the influence of Descartes.
