Therefore nobody can be a good farmer unless he makes his
 labourers both eager and obedient; and the captain
 who leads men against an enemy must contrive to
 secure the same results by rewarding those who act
 as brave men should act and punishing the
 disobedient. And it is no less necessary for a farmer to encourage his
 labourers often, than for a general to encourage his
 men. And slaves need the stimulus of good hopes no
 less, nay, even more than free men, to make them
 steadfast.