If a man is to be a good statesman, he must know the Good
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“Plato, like all mystics, has, in his beliefs, a core of certainty which is essentially incommunicable except by a way of life. The Pythagoreans had endeavoured to set up a rule of the initiate, and this is, at bottom, what Plato desires. If a man is to be a good statesman, he must know the Good; this he can only do by a combination of intellectual and moral discipline. If those who have not gone through this discipline are allowed a share in the government, they will inevitably corrupt it. In the third place:” source