Susan Glaspell's Trifles speaks to a woman's place in society. In its historical context, it addressed a very difference group of people than that of today, but its message is still compelling to the contemporary audience.
A theme is defined as:
...[t]he main idea or the basic meaning of a literary work.
The theme is not the same as the subject. Often, it is not stated outright, but is implicit. The literary work presents one or more "life truths" that the author is trying to share with the audience.
In the play Trifles, the author's inspiration came from an actual murder trial Glaspell covered as a reporter between 1899-1901, by...
...a farmer’s wife, Margaret Hossack, in Indianola, Iowa...accused of killing her husband, John...
Hossack was found guilty. When Glaspell wrote her one-act play in 1916, inspired by these events, things had not changed much for women in American society in those fifteen years. For instance, the right to vote still would not become law until 1920.
The majority of women at that time were wives and mothers. And while the rumblings of change for women's suffrage may have been felt for women living closer to major cities—like New York—women's rights in general would be a very long time coming to the farmlands of the U.S. Isolation among farmers because of long work days and, subsequently, limited social interaction, would have minimized any inkling of change with women's roles and rights.
Mrs. Hale tells the County Attorney that a farmer's wife works very hard, but it goes unnoticed. The men are obviously dedicated to finding a motive that will convict Minnie, however, they never mention justice. The women support this concept (as they would be expected to) at the beginning—doing their duty, as society sees it:
MRS. PETERS. Of course it's no more than [the men's] duty...the law is the law.
However, the women are also challenged by what the men say and how they act. We can infer that Minnie has been physically abused by her husband, but this possibility does not occur to the men—and would it really matter?
The first significant incident takes place when the women find the broken jars of jelly:
COUNTY ATTORNEY. I guess before we're through she may have something more serious than preserves to worry about.
HALE. Well, women are used to worrying over trifles.
(The two women move a little closer together.)
Note the stage direction—it signals a physical and emotional connection between the women, and a noticeable step away from the men, who have just said that the things that completely fill a woman's life are trifles—things of little value.
Ironically, the men literally and figuratively convey that nothing of importance could come from the kitchen...to help their case:
COUNTY ATTORNEY. You're convinced that there was nothing important here--nothing that would point to any motive?
SHERIFF. Nothing here but kitchen things.
But it is in this "woman's place" that the women find evidence—the dead bird. This would provide the men with "probable cause." However, the women have also had the chance to discover how ugly Minnie's life had become: they comprehend her desperate circumstances, and they can empathize with the intense pain that drove her to kill the man that violently destroyed her only source of comfort. Their silence protects Minnie.
The story speaks, then, to the theme of duty vs. justice; the solidarity of womanhood; and, the domination of women by a patriarchal society.