Native American oral literature was an oral tradition that was not recognized by Western scholars until the late 1800s. Types of oral literature included myths, creation myths, trickster tales, and songs. Stories taught moral lessons and conveyed practical knowledge about nature. Animals and humans were often interchangeable, and origin myths sometimes featured animals as creators. Literature used metaphor, similes, and pictographs. The Iroquois constitution from around 1400 CE was influenced by a vision of cultural ideals of peace. It emphasized feminine traits like nurturing and deemphasized masculine aggression. It also expressed stewardship of the earth and optimism for the future.