This essay argues that Dr. Seuss's "The Lorax" (1971) successfully popularized the environmental message that Wallace Stegner presented in his largely forgotten essay "Conservation Equals Survival" (1969). The Seussian language and illustrations have inspired readers, particularly children, to consider and, more importantly, to engage in environmentally sustainable practices. Both Seuss and Stegner wanted to raise the common readers' ecological literacy by alerting them to the dangers posed by modern industrial society and their role in achieving solutions. However, Stegner's essay quickly disappeared from the public consciousness, while Seuss's story remains relevant more than 40 years later, and his character, the Lorax, has become an important part of the environmentalist vernacular. Of particular interest is both authors' use of one word, "unless," to direct individual readers to work together for a sustainable future. Seuss successfully engaged readers to become aware of the needs of the environment and take personal responsibility in caring for their own ecosystems.