MIT economist Paul A. Samuelson, the Nobel laureate whose mathematical analysis provided the foundation on which modern economics is built and whose textbook influenced generations of students, died December 13 at his home in Belmont, MA. He was 94.

Samuelson, an Institute Professor emeritus, was one of the world’s leading economists for more than half a century. When he became the first American to win the Nobel Prize in economics, the Swedish Royal Academy said he had “done more than any other contemporary economist to raise the level of scientific analysis in economic theory.”

Samuelson produced the best-selling economics text of all time, Economics. Originally published in 1948, it was the first to explain the principles of Keynesian economics to beginning students. “I don’t care who writes a nation’s laws–or crafts its advanced treatises–if I can write its economics textbooks,” he later wrote. The book has been translated into more than 40 languages and has sold nearly four million copies.

Samuelson’s contributions to his field were so numerous and fundamental that they lend themselves to description in more general terms. “If you did a time-and-motion study of what any modern economist does at work, you would find that an enormous proportion of standard mental devices trace back to Paul Samuelson’s long lifetime of research,” says Robert Solow, an Institute Professor emeritus. “What I can add about my beloved friend of 60 years is that he had a marvelous intuition about how a market economy had to be. ‘It must work like this,’ he would say. ‘Now all we have to do is prove it.’ There was no one like him.”