all use or exploitation of animals that causes pain, suffering, or fear." Rationale The values that shaped HSUS's formation in 1954, came in some degree from the humane movement that originated in the 1860s in the United States. The idea of kindness to animals made significant inroads in American culture in the years following the Civil War. The development of sympathy for creatures in pain, the satisfaction of keeping them as pets, and the heightening awareness about the relationship between cruelty to animals and interpersonal violence strengthened the movement's popular appeal. The most immediate philosophical influence on 1950s-era advocates, including those associated with HSUS, was the reverence-for-life concept advanced by Albert Schweitzer. Schweitzer included a deep regard for nonhuman animals in his canon of beliefs, and animal advocates laboring to give their concerns a higher profile were buoyed by Schweitzer's 1952 Nobel Peace Prize speech, in which he noted that "compassion, in which ethics takes root, does not assume its true proportions until it embraces not only man but every living being." Myers and his colleagues found another exemplar of their values in Joseph Wood Krutch (1893–1970), whose writings reflected a deep level of appreciation for wilderness and for nonhuman life. With The Great Chain of Life (1957), Krutch established himself as a philosopher of humaneness, and in 1970, HSUS' highest award was renamed in his honor. The growing environmental movement of the early 1970s also influenced the ethical and practical evolution of HSUS. The burgeoning crisis of pollution and wildlife-habitat loss made the public increasingly aware that humans needed to change their behavior toward other living things. By that time, too, the treatment of animals had become a topic of serious discussion within moral philosophy. The debate spilled over into public consciousness with the publication of Peter Singer's Animal Liberation (1975). Singer's book sought to recast concern for animals as a justice-based cause like the movements for civil rights and women's rights. Most of what Singer wrote concerning the prevention or reduction of animals' suffering was in harmony with HSUS's objectives. Singer's philosophy did not rest upon the rights of animals, and he specifically rejected the framework of rights in favor of a utilitarian assessment that focused on animal sentience. His principal concern, like that of HSUS, was the mitigation and elimination of suffering, and he endorsed the view that ethical treatment sometimes permitted or even required killing animals