( CNN ) -- Reporters Carl Bernstein and Bob Woodward relied on FBI insider W. Mark Felt as a reliable but anonymous source for their stories on the Watergate scandal that led to President Richard Nixon 's resignation in 1974 . Carl Bernstein says `` Deep Throat 's '' information on Watergate was `` absolutely invaluable . '' Felt , referred to as `` Deep Throat '' in the Washington Post stories and in Woodward and Bernstein 's book `` All the President 's Men , '' died Thursday in California at 95 . He revealed his identity for the first time in 2005 . Bernstein never met Felt until this year , but praised his courage during an interview Friday on CNN 's `` American Morning . '' AM : What are your thoughts on the occasion of Mark Felt 's death ? Bernstein : I think it 's a little emotional , even though he was 95 years old . He was integral to our coverage . He was one of many sources in Watergate who had both the intelligence and the courage to tell the truth . And in his own organization he was one of the few , and he was near the top . What his information enabled us to do was to confirm stories that we had really obtained elsewhere , more than anything else , rather than give us that much primary information . But it was invaluable , and he performed a great act of courage and national service . Watch a video obituary of W. Mark Felt » . AM : The way that he was portrayed by Hal Holbrook in `` All the President 's Men '' was he would give your partner Bob Woodward a little bit of a tease and say , `` I 'm not going to tell you anything more than that ; you 've got to follow the trail . '' Was that an accurate portrayal ? Bernstein : Yeah . Yeah , that 's what we did . But his knowledge gave us a grounding and assurance that we were right in what we were saying and reporting . [ He gave us ] a certainty in a situation where you had the leader of the free world attacking the press every day , making our conduct -- Woodward 's , myself 's , the Washington Post 's -- the issue in Watergate rather than the conduct of the president and his men . So I think Mark Felt 's confirming this information ( and occasionally he gave us some important information that we had n't obtained , toward the end , elsewhere ) , it was absolutely invaluable . AM : It was always Bob Woodward 's intention to keep the identity of Deep Throat secret until the occasion of Mark Felt 's death . Bernstein : Well , we both kept it . I knew who he was . The two of us knew . AM : Was it a surprise when it came out in 2005 ? Bernstein : To both of us . It was a total surprise , even though I 'm a contributing editor at Vanity Fair magazine and they disclosed it . They scooped everybody on that one . Yeah , we were surprised . Bob and I went out to San Francisco a few weeks ago ; we had a speech out there . And we went to see Mark Felt , and we had a kind of wonderful couple of hours with him . He knew we were coming ; he was looking forward to it . But he had been very ill , and it was a kind of closing of the circle , and it was a wonderful experience . AM : Was that the first time you had met him in person . Bernstein : First time I had met him , yes . Bob had met him as a young ensign in the Navy , when he was a messenger at the Pentagon and had renewed the acquaintance . AM : So what did you think of him when you met him ? Bernstein : First of all , I was aware that he was 95 years old and in the last stages of his life . But I was amazed at his relative vigor given the fact that he had been quite ill . I was also surprised that there were some moments of clarity , because he had dementia . AM : His family , when the news came out in 2005 , declared him to be an American hero . Would you agree ? Bernstein : Obviously he is . Look , Watergate was a constitutional crisis in a criminal presidency . And he had the guts to say , `` Wait . The Constitution is more important in this situation than a president of the United States who breaks the law . '' It 's an important lesson , I think , for the country and for people in our business , as well .
Watergate reporter Bernstein knew who Mark Felt was ; only Woodward contacted him . Comment: Bernstein : Felt `` performed a great act of courage and national service ''