Suppose Stan owns a piece of property with a large lake. Initially, Stan and his family were the only people who swam in the lake. Then Stan started selling tickets to people who wanted to go swimming in the lake. When Stan died, he left the lake and the land it was on to the state, stipulating that the lake be left open to the public for swimming. Due to the lake’s remote location, it was never crowded. After Stan died, the lake became a ______ good.