IX (Gustavi Seleni). The pseudonym itself is a cryptic reference to his name, Gustavus anagrams (with U=V) to Augustus, the surname is a play on the Greek goddess of the moon (Selene). The book on cryptography is largely based on earlier works by Johannes Trithemius. The duke employed the scholar Justus Georg Schottel as tutor of his sons; he also kept an active correspondence with Johannes Valentinus Andreae, a founder of the esoteric Rosicrucianism movement. In 1632 he met with Prince Louis I of Anhalt-Köthen and joined his Fruitbearing Society. Augustus died at Wolfenbüttel and was succeeded by his eldest son Rudolph Augustus. Marriage and children In December 1607 he married Clara Maria of Pomerania-Barth, the eldest daughter of the Griffin duke Bogislaw XIII of Pomerania. The marriage produced two stillborn children. Clara Maria died in February 1623. In October 1623 he married Dorothea of Anhalt-Zerbst, daughter of the Ascanian prince Rudolph of Anhalt-Zerbst. They had the following children: Henry August (1625–1627) Rudolph Augustus (1627–1704), Duke of Brunswick-Lüneburg and Duke of Brunswick-Wolfenbüttel married firstly, in 1650 Countess Christiane Elisabeth of Barby (1634-1681) married secondly, in 1681 Rosine Elisabeth Menthe (1663-1701) Sibylle Ursula (1629–1671) married in 1663 Duke Christian of Schleswig-Holstein-Glücksburg (1627-1698, son of Philip, Duke of Schleswig-Holstein-Sonderburg-Glücksburg) Klara Auguste (1632–1700) married in 1653 Duke Frederick of Württemberg-Neuenstadt (1615-1682) Anton Ulrich (1633–1714), Duke of Brunswick-Wolfenbüttel married in 1656 princess Elisabeth Juliane of Schleswig-Holstein-Norburg (1634-1704). Dorothea died in September 1634 and in 1635 Augustus married Duchess Elisabeth Sophie of Mecklenburg, daughter of Duke John Albert II of Mecklenburg. They had two surviving children: Ferdinand Albert I (1636-1687), Duke of Brunswick-Lüneburg married in 1667 Christine of Hesse-Eschwege (1649-1702) Marie Elisabeth (1638-1687) married firstly, in 1663 Adolf William, Duke of Saxe-Eisenach married secondly, in 1676 Albert V, Duke of Saxe-Coburg. Ancestors References External links Bibliotheca Augusta 1579 births 1666 deaths People from Dannenberg (Elbe) Princes of Wolfenbüttel Pre-19th-century cryptographers German chess players German chess writers German male non-fiction writers New House of Brunswick