in Leiden. In these years Prince Frederick Henry of Orange, Huygens' confidante and protector, became increasingly ill, and died in 1647. The new stadtholder, William II of Orange, greatly appreciated Huygens and gave him the estate of Zeelhem, but he died too in 1650. The emphasis of Huygens' activities moved more and more to his presidency of the Council of the house of Orange, which was in the hands of the young Prince inheritor, a small baby. He traveled frequently during that time, in connection with his work. There were however strong disagreements between the baby's widowed mother in law Amalia van Solms, and her own widowed daughter in law Mary, Princess Royal, (4 November 1631 – 24 December 1660, aged 29) on even the name for christening the Dutch-English Royal newborn. In 1657, his son Philips died after a short sickness during his Grand Tour while in Prussia. In that same year Huygens became seriously ill, but healed in a miraculous manner. In 1680 Constantijn Jr. moved with his family out of the house of his father. To stop the gossiping which started shortly afterwards, Huygens write the poem Cluijs-werck, in which he shows a glimpse of the latter stages of his life. Later career and French knighthood Huygens started a successful career despite his grief over the death of his wife (1638). In 1630 he was appointed to the Council and Exchequer, managing the estate of the Orange family. This job provided him with an income of about 1000 florins a year. In that same year he bought the heerlijkheid Zuilichem and became known as Lord of Zuilichem (in Dutch: Heer van Zuilichem). In 1632, Louis XIII of France - the protector of the famous exiled jurist Hugo Grotius - appointed him as Knight of the Order of Saint-Michel. In 1643 Huygens was granted the honor of displaying a golden lily on a blue field in his coat of arms. In 1634 Huygens received from Prince Frederick Henry a piece of property in The Hague on the north side of the Binnenhof. The land was near the property of a good friend of Huygens, Count Johan Maurits of Nassau-Siegen, who built his house, the Mauritshuis, around the same time and using the same architect, Huygens' friend Jacob van Campen. Correspondence Aside from his membership in the Muiderkring (which was not as formerly supposed, an official club), at the