Subjects of Special Interest to the Landgraves: Mathematics, astronomy and alchemy
In 1580, under William IV, the book collection of the landgravial house was compiled for the first time. However, the library, which was housed in the langravial mews (Renthof), grew much less quickly than the court chapel's collection of sheet music.
Since the landgravial house did not systematically promote the collection of manuscripts and printed books - except in the area of music - the development of the collections was strongly tied to the changing interests of the respective rulers from the very beginning.
While Landgrave Wilhelm the Wise († 1592) was primarily concerned with theological, astronomical and mathematical issues and amassed a large collection of incunabula and books on these subjects, his son Moritz the Learned († 1632) was intensively occupied with alchemy. - However, his collection of alchemical writings, comprising over 600 manuscripts and prints, was not integrated into the landgravial library until 1675.
Catalogue of Landgrave Maurice the Learned's works
During the Thirty Years' War, under Landgrave William V, Hessian troops plundered church property in Fulda. As a result, the landgrave acquired the Hildebrandlied and a copy of the De bello Iudaico by Flavius Josephus from the 6th century around the year 1632.
In addition, the collection was also enriched by various other outstanding medieval manuscripts, among them some precious late medieval liturgical manuscripts.
Palatine Heritage: The Younger Palatina
An inheritance in 1686 resulted in further significant additions to the library's collection of manuscripts and printed books. After the death of Elector Charles II of the Palatinate († 1685), a grandson of Landgrave William V, and that of his mother Charlotte († 1686), the valuable book collection of the Palatine counts of Heidelberg came to the court in Kassel. This collection was compiled from various older partial collections or newly acquired after the Bibliotheca Palatina had been carried off to Rome as spoils of war.
The Younger Palatina enriched the library of the landgraves with excellent and richly illuminated Renaissance codices, such as the manuscript of the Canzone by Petrarch, the Rules of the Order of the Golden Fleece, or Bocaccio's Il filocolo.