Montesquieu

When a repu­blic has redu­ced a nation to tilling land for it, the citi­zen ought not to be allo­wed to increase the slave’s tri­bute. It was not per­mit­ted in Lacedæmon ; they thought the Helots would till the land bet­ter when they knew that their ser­vi­tude would not increase1 ; they belie­ved the mas­ters would be bet­ter citi­zens when they desi­red no more than they were accus­to­med to having.

Plutarch.