This quote is taken from a national address given by President Gerald Ford in 1974:

My conscience tells me clearly and certainly that I cannot prolong the bad dreams that continue to reopen a chapter that is closed. My conscience tells me that only I, as President, have the constitutional power to firmly shut and seal this book. My conscience tells me it is my duty, not merely to proclaim domestic tranquility but to use every means that I have to insure it. I do believe that the buck stops here, that I cannot rely upon public opinion polls to tell me what is right.

What was the purpose of this speech to the American people?

to announce the resignation of vice president Spiro Agnew
to announce the American troops were being withdrawn from South Vietnam
to announce a pardon for Richard Nixon's crimes in the Watergate Scandal
to announce that he would not run for a full term in office