Paul Samuelson is one of the great economists of the 20th century. He was one of the first ones awarded the Nobel Memorial Prize. His textbook on Principles was the standard text for at least 40 years and the model for all others. He speaks in a two-part interview on the current economic crisis, the crisis in macro theory today, and even a few comments about modern textbooks.
Interesting supplements to this interview are the summary of the history of modern macro theory by Krugman (I have post about it here) and a short history of macro and crises by Brad deLong (I have a post here.).