In 1851 Arthur Schopenhauer published Parerga und Paralipomena. In the second volume he tells a parable. Eine Gesellschaft Stachelschweine drängte sich, an einem kalten Wintertage, recht nahe zusammen. A group of porcupines pressed close together on a cold winter day. They wanted to warm each other, but their quills hurt. So they moved apart, then together again, until they found a distance they could bear. Schopenhauer applies this to people. The need for company drives them together, and their unpleasant qualities push them apart. Die mittlere Entfernung, die sie endlich herausfinden, the middle distance that they finally find, is die Höflichkeit und feine Sitte, politeness and good manners. A person with much eigene, innere Wärme, inner warmth of his own, prefers to stay away from society.