The third volume of Hubert Howe Bancroft's comprehensive compilation focuses on the mythology and languages of the native races of the Pacific states. The text begins with an extensive exploration of speculative thought, analyzing the differences between human speech and animal communication, and tracing the origins of language, myth, and worship from primitive fetichism to polytheism and monotheism. Bancroft details the creation-myths, origin stories, and flood legends of various indigenous groups, notably the Quiché Maya from the Popol Vuh, the Aztecs of Anáhuac, and numerous tribes from California, the Pacific Northwest, and the northern regions. The narrative covers physical myths involving celestial bodies, fire, wind, and water, alongside animal mythology where creatures act as cultural heroes, tricksters, or ancestral figures.
A significant portion is devoted to the pantheon of gods, supernatural beings, and ritual practices, including shamanism, sacrifices, and burial customs. The second half of the volume transitions into comparative philology, providing an exhaustive survey of native languages. Bancroft examines the structural characteristics, grammatical forms, and comparative vocabularies of major linguistic families, including Hyperborean, Columbian, Californian, Shoshone, Pueblo, New Mexican, Aztec, Central American, and Maya-Quiché tongues. The work concludes that these diverse myths and languages, though fragmentary and often misunderstood by contemporary observers, reflect genuine psychological structures and historical undercurrents that reveal the inner life of aboriginal populations.