George Orwell's Keep the Aspidistra Flying is as topical today as when it was first published in 1936. Orwell's treatment of the subject of maturing and taking responsibility for one's life is hugely poignant and his prose is staggeringly good. I love my tatty, browning copy but there are several newer editions that could tempt me.
I can't write about George Orwell without mentioning Down and Out in Paris and London. Along with Keep the Aspidistra Flying this was one of my 'formative' reads and is among the novels that switched my son onto reading beyond genre fiction. Down and Out is an account of Orwell's two years spent living as a homeless person before the second world war. His courage and humanitarianism are evident throughout and his prose is deeply moving.
Both books are short, utterly gripping and will change your life.