About William Petty:
Sir William Petty was an English economist, scientist and philosopher. He first became prominent serving Oliver Cromwell and Commonwealth in Ireland. He developed efficient methods to survey the land that was to be confiscated and given to Cromwell's soldiers. He also managed to remain prominent under King Charles II and King James II, as did many others who had served Cromwell.
Wherefore when a man giveth out his money upon condition that be may not demand it back until a certain time to come, he certainly may take a compensation for this inconvenience which he admits against himself.William Petty
Here we are to remember that in consequence of our opinion that labor is the Father and active principle of wealth, as lands are the Mother, that the state by killing, mutilating, or imprisoning their members do withal punish themselves.William Petty