“Imagine a group of porcupines trying to survive a cold winter. They huddle together for warmth, only to then poke one another with their quills and withdraw. Schopenhauer wrote that human relationships are like this: Much as cold drives the animal porcupines together, ‘the need of society drives the human porcupines together, only to be mutually repelled by the many prickly and disagreeable qualities of their nature.'”