"On a 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 discovered the proper distance from which they could best tolerate one another. Thus the need for society, which springs from the emptiness and monotony of men’s lives, drives them together; but their many unpleasant and repulsive qualities and insufferable drawbacks once more drive them apart. The mean distance which they finally discover, and which enables them to endure being together, is politeness and good manners. Whoever does not keep to this, is told in England to ‘keep his distance.’ By virtue thereof, it is true that the need for mutual warmth will be only imperfectly satisfied, but, on the other hand, the prick of the quills will not be felt. Yet whoever has a great deal of internal warmth of his own will prefer to keep away from society in order to avoid giving or receiving trouble and annoyance."
Arthur Schopenhauer. Parerga und Paralipomena Vol. 2 Chapter XXXI