MASKS AND THE FALSE FACE SOCIETY

The Iroquois believed that the evil spirits that caused disease could be scared away by special masks. The masks were built into a live tree, and the Iroquois would carve a face on the tree resembling a "tree spirit" or a "healing spirit." Finally, the section of the tree with the face was cut out and an animal tail was sometimes added. In addition to wooden masks, masks fashioned from corn husks were also created. Men wore the masks but women tended the masks. The men would chant, dance, and sing wearing the mask to ward off the evil spirits that caused the sickness.

There were three classes of supernatural phenomena: spirits, ghosts of the dead, and the gods. 

At a man's death, his spirit departed for the afterlife.  Iroquois did not believe people ate food after death and therefore there was no reason to hunt.
The dead man's ghost maintained an interest in the tribe. Special wintertime feasts were held for ghosts, who participated unseen in the dancing and the games. 
It was thought ghosts  also accompanied raiding parties, even though they could only watch and not fight. 

But a death reduced the collective power of a clan and so Iroquois families conducted "Requickening" ceremonies where  the dead person's name and duties was transferred to a successor. People of high status were replaced from within the clan,  but at some point it was necessary to get new people from outside the village to replace the dead. The Iroquois counted on warfare to help strengthen the family with external replacements taken from captives.

Women of the mourning household could demand a raid to seek captives, who would ease their pain. When the victorious Iroquois returned home with their prisoners, village leaders handed over the prisoners to grieving families, whose elders then could decide to either adopt them or execute them

CREATION MYTH

    "Long before there were human beings, there were Sky People. They dwelled in the celestial world. In those days there was no sun. All light came from the large white blossoms on the celestial tree that grew in front of the Lodge of the Sky Chief. This Sky Chief had married a young wife. In time, this wife, Sky Woman, began to show signs that she would soon bear a child.
    There was a troublesome being, called Firedragon, in the Sky World. Firedragon was always spreading rumors. Now he whispered to Sky Chief that the child who was about to be born would not be his. In a fit of anger and jealousy, Sky Chief uprooted the great celestial tree in front of his lodge. He pushed his wife through the hole where the tree had once stood.
  Sky Woman fell rapidly down toward the vast dark waters below. The birds, feeling sorry for her, flew underneath and gently supported her, breaking her fall and carrying her slowly downwards. At the same time, the water animals hurried to make a place for her. Turtle said that he would support a world on his back. The sea animals plunged down into the water looking for some earth. Muskrat succeeded and came up with a large mouthful of earth, which he placed on Turtle's back. The light from the blossoms of the fallen celestial tree shone through the hole where it had stood and became the sun. When Sky Woman landed, everything was in readiness for her, with grass and trees beginning to grow.
    Sky Woman gave birth to a daughter. When this daughter grew to womanhood, she began to be with child. No one knows whether her husband was Turtle or West Wind, but she gave birth to two remarkable twin boys–one good and one evil. The Good Twin was born in the usual way. But the Evil Twin was in a hurry and pushed through his mother's side to be born. In doing so, he killed his mother.
    Sky Woman buried her daughter, and plants miraculously began to grow from various parts of the daughter's body–a tobacco plant, a cornstalk, a bean bush, and a squash vine. This was the origin of all the plants that would be most important to the human beings who would come later.
    The Good Twin and the Evil Twin quickly grew to manhood. As soon as they were grown, they proved true to their names. The Good Twin began creating all sorts of good things: plants, animals, medicinal herbs, rivers, and streams. The Evil Twin began to spoil his brother's work., putting rapids and boulders in the rivers, creating poisonous plants, thorns and briars, diseases, and monsters. The Good and Evil Twins fought against each other to see who would predominate in creation, but the Evil could never overcome the Good. Finally the Good Twin created human beings to enjoy all the good things he had made for them. And that is how it all began.

- Graymont, Barbara. Indians of North America: The Iroquois