German chess book "Chess or the King's Game"

Duke Augustus was one of the most well-read and educated European rulers of his time. The famous Bibliotheca Augusta in Wolffenbüttel is named after him. In his youth, he wrote the first German-language book on chess, "Das Schach oder König-Spiel" ("Chess or the King's Game"). it was published under the pseudonym Gustavus Selenus, the first part of which is a rearrangement of the letters in Augustus, while the second derives from Selene = Luna and forms an allusion to Lüneburg. The book is a great rarity today.