In most American stories where we hear of the first of men emerging from the under-world, it is by climbing a tree. This tree also supports the sky, and is so represented in the native books of the Mayas and Nahuas.[186] The Yurucares of Bolivia relate that their god Tiri, when he would people the earth with men, cleft a tree, and from the opening came forth the various tribes of the world.[187] When the tree was not worshipped as itself, but under a symbolic form, this was usually as the sacred pole or the cross. The sacred pole was found widely among the American Indians. It was planted in the centre of their villages, or, if the tribe was nomadic, it was carried about in an ark or wrapping and set up in a tent by itself in their encampment. It typified the communal life of the tribe and represented the “mystery tree,” which was intimately associated in their legendary origin.[188] In early art the cross as a sacred design is often derived from the conventional figure of a tree, and symbolises the force of life, the four winds, the rain, and the waters. This is notably the case in Mexico and Central America, where we have abundant testimony that this is the origin and meaning of the cross-symbol so frequent on their monuments. The sacred tree is a conspicuous figure in the earliest bas-reliefs of the Chaldeans. It is often represented in a cruciform shape, and frequently a winged seraph is holding up to it a pine cone, the fruit of the sacred cedar, either as an emblem of fertility, or, more likely, as an aspergillum, with which to bedew it from the holy water, which is carried in a bucket in the other hand.[189] That a tree is a “thing of life” it is hard for us even yet to doubt, and we can scarcely avoid being attracted by Fechner’s pleasing theories of a “plant-soul.”[190] The sound of the wind in the leaves, rising from the softest of mystic whispers to the roaring of the wild blast, seems to proceed from some mind or spirit. The Australians say that these are the voices of the ghosts of the dead, communing one with another, or warning the living of what is to come. They and other tribes also believe that it is through understanding this mysterious language that the “doctors,” or shamans, communicate with the world of spirits and derive their supernatural knowledge.[191] Hence we can easily see arose the myth of “the tree of knowledge,” which we find in the earliest Semitic annals and monuments. It belonged to the same species as the oracular oak of Zeus at Dodona, and the laurel of Apollo at Delphi, from the whispers of whose leaves the sibyls interpreted the sayings of the gods.