"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"

This quote by William Petty is a suggestion that labor is the foundation of wealth, which land is the source of it. He is suggesting that when a state punishes its citizens by eliminating, mutilating, or imprisoning them, it is eventually penalizing itself. This is because the labor of its people is necessary to the wealth of the state. Petty is emphasizing the value of labor and the need to secure it. He is also suggesting that punishing citizens is not only unfair, but also damaging to the state's own wealth. This quote acts as a pointer that the labor of people is necessary to the wealth of a state, which punishing citizens is not only unjustified, however also harmful to the state's own wealth.