Read this excerpt from "The World on Turtle's Back." The right-handed twin accused his brother of murdering their mother and their quarrels continued until it was time to bury their mother. With the help of their grandmother, they made her a grave. From her head grew the three sister plants, corn, beans, and squash. From her heart grew tobacco, which people still use to give thanks in ceremony. She is called "our mother" and the people dance and sing to her to make the plants grow.

The excerpt suggests that the Iroquois believed that