In contrast to the natural sciences, where Isaac Newton and Albert Einstein made their major contributions, most economics masterpieces were written when the authors were middle aged. Adam Smith, Karl Marx, John Maynard Keynes, and Milton Friedman come to mind. However, Paul started much earlier, in his 20s; and, even now, his new articles influence the fields of economics and finance.

4.Paul Samuelson is Unique. - Ten Ways to Know Paul A. Samuelson (2006)