Shirley Jackson intentionally leaves the original purpose of the lottery a mystery. It is important to the story that none of the characters should know why or when it started and what was its original purpose. The people just go through the annual ceremony blindly because they have been taught to do so ever since they were tiny children. Little Davy is a good example of how all the people in the story were conditioned to believe in the importance of the lottery.
Mr. Graves took the hand of the little boy, who came willingly with him up to the box. "Take a paper out of the box, Davy," Mr. Summers said. Davy put his hand into the box and laughed. "Take just one paper," Mr. Summers said. "Harry, you hold it for him."
Davy, of course, has no idea that he may be choosing his own death warrant. Chances are he will escape being stoned to death this year because the odds are still four to one in his favor. It turns out that it is his mother who draws the slip with the black mark. So Little Davy is shown how to throw rocks at her when she is stoned to death.
The children had stones already, and someone gave little Davy Hutchinson a few pebbles.
If the people understood what this lottery was supposed to produce or prevent, they would probably realize it was nothing but an ancient superstition. In that case they would probably abandon it. How can stoning a man, woman or child to death insure good crops, as Old Man Warner is suggesting?
"Used to be a saying about 'Lottery in June, corn be heavy soon.'
The lottery might date clear back to the days when human sacrifices were made to some god or goddess in order to procure good crops. If the crops were good, that showed the human sacrifice was effective. If the crops were bad--then maybe they had sacrificed the wrong person. The purpose of the lottery remains a mystery because the author wanted to emphasize that the people were doing something outrageous without even knowing why they were doing it. Tessie Hutchinson is a woman known to everyone in attendance, and everyone seems to like her. Nevertheless, when she draws the fatal black spot, they turn on her without pity.
Tessie Hutchinson was in the center of a cleared space by now, and she held her hands out desperately as the villagers moved in on her. "It isn't fair," she said. A stone hit her on the side of the head.