People generally quarrel because they cannot argue. And it is extraordinary to notice how few people in the modern world can argue. This is why there are so many quarrels, breaking out again and again, and never coming to any natural end. People do not seem to understand even the first principle of all argument: that people must agree in order to disagree. Still less so their imaginations stretch to anything so remote as the end or object of all argument; that they should disagree in order to agree.