Boris the rhetorician is in full voice at the moment, delighting his followers and infuriating his enemies. But is this the purpose of rhetoric?

It was the ancients who invented, or rather deduced, the rules. As the Roman professor of rhetoric Quintilian said: ‘Just as men discovered the art of medicine by observing that some things were healthy and some the reverse, so they observed that, when it came to speaking, some things were advantageous and others not.