Hank Aaron kept the letters -- hundreds of thousands of letters -- that he received when chasing Babe Ruth’s home run record and beyond. They were vile letters, angry letters, threatening letters. Letters that revealed, in no uncertain terms, the dirty underbelly of a nation that has left its most fundamental issues of race and equality unresolved.

Aaron, who died Friday at the age of 86, kept those letters to remind himself -- and everybody else -- that the United States has only progressed to a point, that we still have so far to go.

And yet, even in chronicling the worst of us, Aaron always tried to see the best in us.

“He was very clear-eyed about America, but also a very positive person,” said Sherrilyn Ifill, president and director-counsel of the NAACP Legal Defense Fund (LDF). “That’s one of the wonderful things about being in his company and talking with him about the most difficult issues involving race and opportunity and inequality. There was always a sense of hopefulness and calm and focus about him, which I found incredibly comforting.”

The NAACP LDF is a non-profit that seeks structural changes in our society, promoting racial justice and equality. The organization has been fulfilling this purpose since 1940, but the importance of its work has been particularly pronounced in the past seven years, as the killings of Eric Garner, George Floyd and other Black people at the hands of police have sparked outrage and protest and more widespread support of the cause. Major League Baseball and the owners and baseball operations representatives from all 30 teams donated to the LDF last summer.

Aaron had a decades-long relationship with the LDF. His wife, Billye, has sat on the organization’s board of directors for 45 years. In 2005, the LDF honored him with its Thurgood Marshall Lifetime Achievement Award.

Long after he chased Ruth’s record in the face of so much hate and bile, Aaron continued to fight for civil rights by serving as an authentic sounding board for Ifill and others.

“He’s someone who lived through the arc of an extraordinary period in American history,” Ifill said. “He was always honest if you asked him about race and racism, which is really incredibly refreshing and important. That arc gave him a unique perspective and understanding of the forces that exist in this country that work against the promise of equality.”

Throughout his life, Aaron felt those forces at work. Growing up in the deeply segregated south, in Mobile, Ala., he had experienced both poverty and systemic racism. He had played in the Negro American League and broken the color barrier in the South Atlantic League. He had heard many racist taunts along the way.

• Hank Aaron's most memorable moments

But what Aaron endured as he neared the Babe’s record in 1973 and '74 was on another level entirely. The letters, some of which are in the collection of the National Baseball Hall of Fame in Cooperstown, N.Y., were peppered with slurs, death threats, taunts and racist rage, all because a Black man had dared to hit more home runs than a white icon. By the time he hit his 715th career home run on April 8, 1974, Aaron had two personal security guards. The threats he had received were considered legitimate enough to be investigated by the FBI.

“It really made me see for the first time a clear picture of what this country is about,” Aaron told the New York Times in 1990. “My kids had to live like they were in prison because of kidnap threats, and I had to live like a pig in a slaughter camp. I had to duck. I had to go out the back door of the ballparks. I had to have a police escort with me all the time. I was getting threatening letters every single day. All of these things have put a bad taste in my mouth, and it won’t go away. They carved a piece of my heart away.”

• MLB players pay tribute to Aaron

And this ugliness did not cease when Aaron hit No. 715 or No. 755 or in his post-playing days. Aaron faced derision for the rest of his life. His former teammate, the great Brewers broadcaster Bob Uecker, recalled the treatment Aaron would receive when he returned to Milwaukee to play for the Brewers in 1975 and ’76.

“Del Crandall was our manager when Henry came back, and Del made it a point for me to be with Henry all the time after games,” Uecker said Friday. “Riding a cab back to the hotel or whatever it may be. We were that close. Hank and I were that close. I remember many times seeing hate mail that he got. It was awful. It was really bad. I got mail, because I was talking about him on the air. I got mail from idiotic people who would rip me for talking about Henry. It was bad. Our manager, you should have seen the hate mail that came into the manager’s office from stupid people. They were unbelievably vile and vicious.”

• 'The standard of greatness': HOFers on Hank

When Aaron spoke to USA Today in 2014 about the letters he had kept from 1974, a fresh batch of hate mail flooded the newspaper’s office. "Hammerin’ Hank" was a living legend who remained a victim of our worst sin.

“It’s a part of America, so there you have it,” Ifill said. “No one gets a free pass on this one. So he’s an important link in a chain of exceptional athletes who had to confront that kind of racism and who performed at the highest levels despite it and who also refuse to be silent.”

Ifill wants people to remember Aaron’s story whenever Black athletes face pushback for speaking up about inequality.

“Hank Aaron is someone who was very talented, a mild-mannered person who was attacked in the worst ways and whose family was threatened,” Ifill said. “He played through it and over it. He’s an example of how absurd it is to try to silence athletes, when it was athletes who very often had to encounter the everyday of American racial or ethnic discrimination.”

Aaron encountered that discrimination with calm, with grace, with honesty and with optimism that one day we could be better. Those are the qualities -- far beyond his home run tally -- that many will remember him for.