Arthur Miller (1915 - 2005), Death of a Salesman, 1949.

And old Dave, he'd go up to his room, y'understand, put on his green velvet slippers - I'll never forget - and pick up his phone and call the buyers, and without leaving his room, at the age of eighty-four, he made his living. And when I saw that, I realized that selling was the greatest career a man could want.