Four thousand years ago bands of hunter-gatherers lived in and traveled through the challenging terrain of what is now southwest Texas and northern Mexico. Today travelers to that land can view large art panels they left behind on the rock walls of Rattlesnake Canyon, White Shaman Cave, Panther Cave, Mystic Shelter, and Cedar Springs. Messages from a distant past, they are now interpreted for modern readers by artist-archaeologist Carolyn Boyd. It has been thought that the meaning of this ancient art was lost with the artists who produced it. However, thanks to research breakthroughs, these elaborate rock paintings are again communicating a narrative that was inaccessible to humanity for millennia. In the gateway serpents, antlered shamans, and human-animal–cross forms pictured in these ancient murals, Boyd sees a way that ancient hunter-gatherer artists could express their belief systems, provide a mechanism for social and environmental adaptation, and act as agents in the social, economic, and ideological affairs of the community. She offers detailed information gleaned from the art regarding the nature of the lower Pecos cosmos, ritual practices involving the use of sacramental and medicinal plants, and hunter-gatherer lifeways. Now, combining the tools of the ethnologist with the aesthetic sensibilities of an artist, Boyd demonstrates that prehistoric art is not beyond explanation. Images from the past contain a vast corpus of data—accessible through proven, scientific methods—that can enrich our understanding of human life in prehistory and, at the same time, expand our appreciation for the work of art in the present and the future.