I met Pólya once in person, at his home in Palo Alto in 1975, where he showed me some of his photo albums and discussed some mathematical problems. Richard Wilson was also there. Pólya was a very charming host. Even before then I was a great admirer of Aufgaben und Lehrsätze aus der Analysis. It was one of my inspirations for including lots of solved exercises in my books Enumerative Combinatorics, vols. 1 and 2.