Nelson Mandela lost his freedom, but never his voice.

It resonates even now, five years after his death at the age of 95, in the pages of “The Prison Letters of Nelson Mandela.” This collection of over 250 letters, most never before released, reflect the 27 years he spent in South African prisons, after he was jailed for leading the fight against apartheid as the head of the African National Congress.

The letters — many of which at the time were heavily censored, or never delivered — offer a glimpse into the soul of a man who from November 1962 to March 1990 somehow managed to maintain his dignity and vision. And he did so despite spending part of his sentence smashing stones into gravel on Robben Island, the first of three facilities in which he was incarcerated.

As he wrote to his wife Winnie in 1976:

“The act of writing to you at this moment removes all the tensions and impurities in my feelings and thoughts. It’s the only time I ever feel that some day in the future it’ll be possible for humanity to produce saints who will really be upright and venerable, inspired in everything they do by genuine love for humanity and who’ll serve all humans selflessly.”

The letters show how much he missed his family; he had five children in all, two with Winnie and three with his first wife, Evelyn. They reflect his agony after officials do not allow him to attend the funerals of his mother or his son Thembi, the latter killed in a car accident in 1969.

But more than anything, they show a resolve that was rewarded when apartheid fell, in 1994.

“Remember,” he writes, “that hope is a powerful weapon even when all else is lost.”

Or appears to be, anyway. In reality, Nelson Mandela never lost that, much less his voice.