(Some background: before his first play was published, the formally uneducated half-blind O'Casey had staged plays in his own home, sold newspapers in the street, worked for years on the railways, become an accomplished player of the Irish pipes, had done a spell in the IRB and had been a General Secretary of Jim Larkin's Irish Citizen Army. Beat that.)
At the start of his career as a playwright:
"O'Casey, at the time, was 41. Having worked as a labourer, he had been involved for a period in the Irish language movement and the Labour movement in Dublin and had written a history of the Irish Citizen Army. By 1921 he was deeply embittered at the way in which Irish nationalism had hijacked and consumed radical forces in Dublin."
"Yeats, when he saw Juno, remained his lofty self: "Casey was bad in writing of the vices of the rich which he knows nothing about, but he thoroughly understands the vices of the poor." This use of "Casey" rather than "O'Casey" was an unsubtle put-down, used regularly by both Yeats and Lady Gregory, the dropped "o" suggesting a lower rung in the social ladder, as though O'Casey were someone who delivered coal to the basements of their grand houses."
"The Shadow of a Gunman played first in a city in the throes of civil war, with an armed guard at the door. O'Casey was forcing himself to make his characters larger than his own ideology, but it was the combination - his own sharp and passionate involvement in the politics of his time and his talent for creating memorable characters - that gave the plays their immediacy and their power."