Shirley Jackson's story is connotative of the ancient practice of finding a scapegoat for the evil plaguing a community. In this tradition, a goat was taken from the community, hopefully carrying the evil away with it, and it was tied out to die away from the community. In Jackson's narrative, the meaning of the custom is forgotten but it is followed because, as Old Mr. Warner says, "There's always been a lottery." This unthinking practice of a custom, whether it be sensible or not, is what Shirley Jackson brings to question.
The story brings about questions regarding the historical use of human sacrifice in order to insure a good harvest. While practiced in the past, sacrifice has changed much over the years. While many cultures have forbidden the use of human life in sacrificial events, people can still relate to personal sacrifice for the greater good. I think the horror of sacrificing a life catches many off guard (especially since the idea of the lottery has changed so much).
The theme develops quickly. Many are caught off guard when Tessie is stoned to death. When I teach the story, my students are thinking money or trips will go to the winner.
To me, the sacrifice in "The Lottery" is rooted in ancient pagan rites in the period in which we believed that "the gods" could be placated with an offering, that blood spilled could increase the harvest, for example. In fact, at least two major world religions, Judaism and Christianity, have themes of sacrifice in their texts, for example, Abraham prepared to sacrifice his son, animals being sacrificed at the Temple, and Christ being a sacrifice for all mankind. My guess is that this is a strong human impulse, a way of trying to impose some order on the universe through cause and effect, even when the results show no relationship. This is, of course, just one theme in the story.
The really sinister aspect of "The Lottery" is that the sacrifice is directed by the town's traditions: the drawing and the stoning. Both these actions are steeped in the history of the town, and Jackson plays up the sort of legalism within the process: the careful marking of the slips and the continued use of the decrepit black box. In the end, however, there is nothing redemptive or graceful about Tess's death; Jackson focuses on the brutality of the death, leaving out any mention of the improved quality of life that the villagers believe the sacrifice will bring. Her omission makes Tess's death feel much more like a ritualistic murder.
In "The Lottery" the town sanctions the sacrifice of one individual a year in order to keep the town in God's good graces. The fact that the sacrifice is conducted as a stoning connects the town to the ancient past, which helps enshroud the entire process in mystery and a sense of ancient evil in the modern world.