Remarkable insight into the mind of the irrepressible Christy Brown
There are different forms of imprisonment: the isolation of a jail cell or being trapped inside a contorted body, unable to be understood.
But when people finally make their voices heard they do so in remarkable ways, as if every sentence is an insight into the human heart, amplified by confinement.
You see it in the great poems left by that Dublin poet, the late Davoren Hanna, so disabled that he could only communicate by sitting on his mother's lap and throwing his body towards different letters of the alphabet.
A similar quality shines through every page written by the late Christopher Nolan, who overcame cerebral palsy to write superb books.
But no Irish writer who began life imprisoned by a cage of silence captured the public imagination more than Christy Brown: born in 1932, with such severe cerebral palsy that he could only exercise control over his left foot.
Many of his generation born with this condition lived their lives in silence, inside the sort of institution that Brown's parents were pressured to put him in.
The Browns were ordinary working-class Dubliners, and as Christy was their 12th of 22 children (sadly, only 13 survived) their family home - a two-up, two-down corporation house in Stannaway Road in Kimmage - wasn't ideal to raise a child who needed so much physical care.
But in an act of selfless courage and love his mother, Bridget, and his bricklayer father, Patrick, determined that Christy should be an ordinary part of their bustling family.
He had no conventional schooling. He wrote in a letter in 1963: "I picked up my few scraps of knowledge from watching brothers and sisters at their homework, observing other people, and later on from books borrowed, stolen and occasionally bought in second-hand places on the quays".
He described how he was unable to talk before the age of 17 "except by my eyes and foot and a queer sort of grunting language understood only by my family."
He would never have become internationally famous without the help of professionals such as the dedicated social worker Katriona Delahunt (the first outsider to nurture his talent as a writer and painter) or the pioneering doctor and writer Robert Collis (who helped establish Cerebral Palsy Ireland).
But it really was that boisterous family - especially his shrewd and patient mother - who released him from that cage of silence into a world where not only could he finally speak but where he had so much to say about the human condition.
Today Brown exists in the public mind not so much for his own words as for Daniel Day Lewis' brilliant portrayal of him in the film My Left Foot, based on his memoir which Robert Collis helped to get published in 1954 when Brown was only 22.
Brown grew to dislike this memoir, feeling that he needed to produce a more nuanced book to become a major writer. It took him another 16 difficult years to publish his international bestseller, Down All the Days, in 1970.
Large parts were written in the American home of his lover, Beth Moore, who devised a structured day that allowed him to work for long hours away from alcohol. The novel catapulted him to international stardom, but although it gave him the financial independence and literary respect he craved, it also marked the highpoint of his life and writing career.
The film of his life is accurate in most respects, except for the ending which implies that the future wife was a nurse and that happiness and contentment beckoned amid his newfound fame.
Sadly, his final decade was a darker, unhappier time. Marriage seemed to isolate Brown from family and friends, cut off in Kerry and then Somerset, where he died, aged 49, in 1981 after choking on a meal.
Without this film his extraordinary story might have been forgotten. That would be a tragedy, because Brown was a fascinating figure steeped in humanity, acutely conscious of his difficulties, sensitive as a writer and often seething with frustration at the difficulty of communication.
This week a fascinating exhibition, Dear Christy: The Christy Brown Collection, opens in the Little Museum of Dublin on St Stephen's Green. Running until August 2, it throws a new light on Brown as a man, a writer and a painter.
It is based on Brown's personal archive which was auctioned in London last year. A generous financial donation allowed this unique archive to stay in Ireland, where it now goes on public display for the first time.
It contains unique and previously unseen artefacts, ranging from childhood mementos and nude sketches to unpublished poems and an early letter to Katriona Delahunt in which he mentions his ambition to become an artist.
As curator Simon O'Connor says, the exhibition "celebrates the life of a truly inspirational Dubliner". It reveals Brown's struggles and how those who loved him inspired him to create paintings, a classic memoir, four novels and four collections of poetry - using only his left foot.
Brown lived in an Ireland where people who were different were expected to stay out of sight.
The exhibition by its nature is a tribute to his remarkable mother - brilliantly played by Brenda Fricker in the film - who refused to believe him incapable of thought and spent endless days working with him until he famously made his first chalk mark on her kitchen floor.
The simple achievement of writing the word "mother" in chalk was as astonishing as the books for which he later became famous.
But with any writer the true person is often glimpsed in the unpublished words - these discarded drafts, childhood poems, paintings and private letters that, for the first time, the public will glimpse this week.
Go along and salute a remarkable Dubliner and a complex, troubled, joyous and fascinating human being.
Dear Christy: The Christy Brown Collection runs at the Little Museum of Dublin from Friday until August 2