Irish rock star Bono (R) and former South African president Nelson Mandela are pictured after meeting at Mnadela's home in Jo
Juda Ngwenya/AFP/Getty Images

Just two weeks ago, U2 released their first new song in four years, a single from the Nelson Mandela biopic, Mandela: Long Walk to Freedom.Today, the day after Mandela's death at 95, frontman Bono published a letter in Time honoring the life of his friend and idol.

"As an activist I have pretty much been doing what Nelson Mandela tells me since I was a teenager, " he wrote in the opening.

He went on to speak about the Irish connection to Mandela's anti-apartheid efforts. "From our point of view, the question as to how bloody South Africa would have to get on its long road to freedom was not abstract," Bono explained, referencing the struggles that wracked Ireland during U2's early days.

Bono also paid tribute to the venerated leader's fight against poverty and dedication to progress. "Without Mandela, would Africa be experiencing its best decade of growth and poverty reduction?" Bono wrote. "His indispensability can’t be proved with math and metrics, but I know what I believe…"

Bono is a multi-year Nobel Peace Prize nominee himself and has dedicated the bulk of his humanitarian efforts to Africa. In 2008, he was crowned as the annual "Man of Peace" by the Nobel laureates for his work tackling African debt, poverty and disease.

But in addition to Mandela's humanitarian work, the "Bloody Sunday" singer also spoke to the beloved politician's personal qualities, including his humor and charm.

"He had humor and humility in his bearing, and he was smarter and funnier than the parade of world leaders who flocked to see him. He would bait his guests: 'What would a powerful man like you want with an old revolutionary like me?'"

Despite being an emotive person, Bono explained in closing that Mandela was physically unable to cry as a result of injury to his tear ducts after many, many years of working at a limestone mine while he was imprisoned.

"Mandela could still see," he wrote. "But the dust damage to his tear ducts had left him unable to cry. For all this man’s farsightedness and vision, he could not produce tears in a moment of self-doubt or grief.  He had surgery in 1994 to put this right. Now, he could cry. Today, we can."

In case you aren't done crying yet, check out Bono and company's musical tribute to Mandela, the poignant and impassioned anthem "Ordinary Love" below.