Indian economist Amartya Sen, applying this thinking to human freedom itself, argued in his 1999 book "Development as Freedom" that human free time was the only real service, and that sustainable development was best defined as freeing human time. Sen won The Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel in 1999 (sometimes incorrectly called the "Nobel Prize in Economics") and based his book on invited lectures he gave at the World Bank.