Why did Deep Throat leak to Washington Post reporter Bob Woodward?

Woodward and Carl Bernstein write in their 1974 book, All the President’s Men, that Deep Throat shared his secrets to “protect the office” of the presidency and “effect a change in its conduct before all was lost.” Woodward amended his source’s purely patriotic motives in his 2005 book, The Secret Man: The Story of Watergate’s Deep Throat. In it, Woodward held that Deep Throat — whom he confirmed was W. Mark Felt, a former high-ranking FBI man who outed himself as the leaker — supplied him with information to protect the FBI from the meddling Nixon White House. That harmonized with the rationale offered in A G-man’s Life: The FBI, Being ‘Deep Throat,’ and the Struggle for Honor in Washington, Felt’s 2006 book published with the guiding hand of a co-writer (Felt was 92 and suffering from dementia): that Deep Throat leaked to Woodward to “spark a broader investigation” by the Justice Department of the break-in.