In "The Garden Party" the theme of "epiphany" is conveyed through the stream-of-consciousness narrative that envelops the entire experience as it is told from the focalized perspective of Laura.
A well-to-do young woman with little to no worries in life, Laura has reached her "coming of age" years and has been bestowed with the responsibility of preparing and overlooking one of the several high society garden parties that ladies of her class often put together.
This experience alone brings Laura a sense of slight achievement, as she has been trusted with a truly detailed and somewhat tedious task. However, the reader can sense that Laura internally desires something else.
First came the conversation with the four working men who were at the site of the party putting up the marquee. Laura's class clashed against an inner willingness to communicate with these men; her nature prevailed and this is perhaps the first time in Laura's life where she actually speaks one on one with "common" people.
Oh, how extraordinarily nice workmen were, she thought. Why couldn't she have workmen for her friends rather than the silly boys she danced with and who came to Sunday night supper? She would get on much better with men like these.
Apparently this leaves a slight mark on her psyche, as later on in the story the local village's carter dies and the news of his sudden death really seems to move her. This is the second instance where Laura feels moved to be a part of the world, and not just an over-protected "princess".
The progression of the garden party is a metaphor of the passing of time, and the welcoming of maturity. As with many Mansfield stories, the main character is on the verge of experiencing an "epiphany", or life changing experience that will change them forever.
Finally, when Laura enters the home of the dead carter to pay her respects, she sees his young and beautiful demeanor and she is moved to tears. This part of her epiphany represents the shock at realizing that life is just too short and unexpected to be placing so much weight in ephemera such as decorative parties, and on the pleasing of "beautiful people". Life has many dimensions and to live in only one echelon is to rob ourselves of it. This is what Laura ultimately realizes; life is different, much different, than what she has been brought up to believe.