Flint arrowheads, spearheads, and axe heads made by prehistoric Europeans were generally considered before the eighteenth century to be a naturally produced stone that formed in storm clouds and fell with lightning. These stones were called ceraunia, or thunderstones, and it was not until the sixteenth century that their status as a natural phenomenon was challenged. During the seventeenth century natural historians and antiquaries began to suggest that these ceraunia were not thunderstones but ancient human artifacts. I argue that natural history museums, European contact with the stone-tool using peoples in the New World, and the close relationship between natural history and antiquarianism were critical to this reinterpretation of ceraunia. Once these objects were recognized to be ancient artifacts they could be used to investigate the earliest periods of human history from sources other than texts.