from Natural News:

History teaches us that some ancient civilisations killed their children to change the weather. They used to practice child sacrifice to appease their gods in an attempt to court their good graces. Those primitive peoples believed that through human sacrifice, the forces of nature could be coerced in their favour. For example, one of the ways the Aztecs honoured their gods was by killing people in a field with arrows so that their blood might fertilise the land.