Der Zauberberg
The German novelist Thomas Mann mentions Nickel in his famous book "The Magic Mountain", bringing up a relatively forgotten quote by the Superior-General about love for one's fatherland, which Nickel called "a plague with the most certain death of Christian love". This notion of Nickel's has already been touched on in the Finnish philosopher Edward Westermark's book "The Origin and Development of Moral Ideas", back in 1917.