Rent-seeking is an attempt to obtain economic rent (i.e., the portion of income paid to a factor of production in excess of what is needed to keep it employed in its current use) by manipulating the social or political environment in which economic activities occur, rather than by creating new wealth. Rent-seeking implies extraction of uncompensated value from others without making any contribution to productivity. The classic example of rent-seeking, according to Robert Shiller, is that of a feudal lord who installs a chain across a river that flows through his land and then hires a collector to charge passing boats a fee (or rent of the section of the river for a few minutes) to lower the chain.