Director of the Mauritshuis museum, 1889-1909, connoisseur and art collector. Bredius was raised in a wealthy family. His father was Johannes Jacobus Bredius a director of a powder factory in Amsterdam. His family collected Chinese porcelain and 17th-century Dutch paintings, which Bredius would build upon. His mother died when he was only ten. Early in his career, he intended to become a concert pianist, but realized after three years of study that he would never become an outstanding musician.

Architectural historian. Rosenau's father was Albert Rosenau (d. 1923), a medical doctor and her mother Klara Lion (Rosenau). She was raised in Monte Carlo and in Bad Kissingen, Germany, where she was privately tutored. After receiving her abitur in 1923, she studied art history at various universities, including Munich under Heinrich Wölfflin, Halle, Berlin under Adolph Goldschmidt, Bonn under Paul Clemen and finally Hamburg under Erwin Panofsky.