What is the author's message?

I believe the author's main message was to convey the necessity of allusion in life.

Blanche dwells in illusion; fantasy is her primary means of self-defense, both against outside threats and against her own demons. But her deceits carry no trace of malice, but rather they come from her weakness and inability to confront the truth head-on. She is a quixotic figure, seeing the world not as it is but as it ought to be. Fantasy has a liberating magic that protects her from the tragedies she has had to endure. Throughout the play, Blanche's dependence on illusion is contrasted with Stanley's steadfast realism, and in the end it is Stanley and his worldview that win. To survive, Stella must also resort to a kind of illusion, forcing herself to believe that Blanche's accusations against Stanley are false so that she can continue living with her husband.