According to one criticism, the Expressionist play, The Glass Menagerie by Tennessee Williams,
...identifies the conquest of reality by illusion as a huge and growing aspect of the human condition in its time.
As a memory play, lighting and music play an integral role in the plot and development of character. In Tom Wingfield, the memory of having abandoned his mother, and especially Laura, haunts him. In fact, these memories confine him as restrictively as if he were yet in the small apartment. Thus, the lighting of the final scene expresses the intimacy and fragility of this particular part of the drama. Williams's stage directions state that the interior scene is played simultaneously with Tom's closing speech; it is as though he were viewing his family through soundproof glass, Williams directs.
Relentlessly pursued by memory, Tom looks into a lighted window of a perfume store. There he sees miniature bottles, transparent in delicate colors "like bits of a shattered rainbow"--symbolic of Tom's shattered dreams as well as Laura's and Amanda's broken hopes. Then, with the suddenness of memory, Tom thinks of his delicate sister--"Blue Roses" as Jim calls her--and he is consumed with guilt,
Oh, Laura, Laura, I tried to leave you behind me, but I am more faithful than I intended to be! I reach for a cigarette, I cross the street, I run into the movies or a bar, I buy a drink, I speak to the nearest stranger - anything that can blow your candles out!
With light already having been associated with memory, Tom wishes that he could "blow out" the light and love of Laura and escape his unfaithfulness to this dear, delicate creature who has needed him.
At the same time, through the window the audience sees the forsaken Laura, from whose face, Williams previously has written, the "holy candles in the altar...have been snuffed out," as for only a moment Jim has made her feel normal,only to reveal that he is engaged and her illusions are ended. Now, she bends over the candles that are still burning after Jim's departure.
For nowadays the world is lit by lightning! [theme of illusion] Blow out your candles, Laura--and so goodbye....
Laura blows the candles out, symbolizing the "snuffing out" of her fragile hope that she might find love. In addition, having created and completed the play, this "snuffing out" may also signify that Tom has released himself from his own memories through the purging of artistic endeavor.