This is an open-access version of The Dragon and the Rainbow: Man's Oldest Story, originally published by Brill under a CC BY-NC-ND 4.0 license. The Dragon and the Rainbow: Man’s Oldest Story is a comprehensive study in historical linguistics and comparative mythology by the late linguist Robert Blust. In this work, Blust argues that the "dragon" archetype—a composite monster often associated with water and the rainbow—is not a late cultural invention, but a concept that dates back to the very beginnings of human symbolic thought. Using evidence from over 600 cultures across the globe, Blust traces the "Rainbow Serpent" and dragon motifs back to a common ancestral experience. He proposes that these myths originated as an early human attempt to explain the atmospheric phenomenon of the rainbow, linking it to a powerful, often dangerous, supernatural entity. This volume represents a significant interdisciplinary contribution to the study of the human mind, language evolution, and the deep history of global folklore.