Complex sentence: He was royal librarian and tutor and advisor of King Gustavus Adolphus of Sweden and his works have ben known to be read by contemporary mystics such as Jakob Böhme (Lewis 1914).
Split into simpler sentences: He was royal librarian, tutor, and adviser of King Gustavus Adolphus of Sweden. Contemporary mystics such as Jakob Böhme have studied his works (Lewis 1914).