“One cold winter’s day, a number of porcupines huddled together quite closely in order through their mutual warmth to prevent themselves from being frozen. But they soon felt the effect of their quills on one another, which made them again move apart. Now when the need for warmth once more brought them together, the drawback of the quills was repeated so that they were tossed between two evils, until they had discovered the proper distance from which they could best tolerate one another.”

– Arthur Schopenhauer.

This quote was used to open a chapter on Kant and the Concept of Respect for Persons. I think the author could not have picked a more appropriate extract.