In reality... the greater part of modern property, whether, like mineral rights and urban ground-rents, it is merely a form of private taxation which the law allows certain persons to levy on the industry of others, or whether, like property in capital, it consists of rights to payment for instruments which the capitalist cannot himself use but puts at the disposal of those who can, has as its essential feature that it confers upon its owners income unaccompanied by personal service.