widely considered today to be the most influential economist of the 20th century. Keynes rejected the basic tenet of classical economics that free markets would lead to full employment by themselves. Consequently, he recommended government intervention to stimulate aggregate demand in the economy, a macroeconomic policy now known as Keynesian economics. Keynes also believed that capital accumulation would reach saturation at some point in the future. In his essay from 1930 on The Economic Possibilities of Our Grandchildren, Keynes ventured to look one hundred years ahead into the future and predict the standard of living in the 21st century. Writing at the beginning of the Great Depression, Keynes rejected the prevailing "bad attack of economic pessimism" of his own time and foresaw that by 2030, the grandchildren of his generation would live in a state of abundance, where saturation would have been reached. People would find themselves liberated from such economic activities as saving and capital accumulation, and be able to get rid of 'pseudo-moral principles' — avarice, exaction of interest, love of money — that had characterized capitalistic societies so far. Instead, people would devote themselves to the true art of life, to live "wisely and agreeably and well." Mankind would finally have solved "the economic problem," that is, the struggle for existence. The similarity between John Stuart Mill's concept of the stationary state (see above) and Keynes's predictions in this essay has been noted. It has been argued that although Keynes was right about future growth rates, he underestimated the inequalities prevailing today, both within and across countries. He was also wrong in predicting that greater wealth would induce more leisure spent; in fact, the reverse trend seems to be true. In his magnum opus on The General Theory of Employment, Interest and Money, Keynes looked only one generation ahead into the future and predicted that state intervention balancing aggregate demand would by then have caused capital accumulation to reach the point of saturation. The marginal efficiency of capital as well as the rate of interest would both be brought down to zero, and — if population was not increasing rapidly — society would finally "... attain the conditions of a quasi-stationary community where change and progress would result only from changes in technique, taste, population and institutions ..." Keynes believed this development would bring about the disappearance of the rentier class, something he welcomed: Keynes argued that