Word History: Agnostics do not deny the existence of God—instead, they hold that one cannot know for certain whether or not God exists. The term agnostic was coined by the 19th-century British scientist Thomas H. Huxley, who believed that only material phenomena were objects of exact knowledge. He made up the word from the prefix a-, meaning "without, not," as in amoral, and the noun Gnostic. Gnostic is related to the Greek word gnōsis, "knowledge," which was used by early Christian writers to mean "higher, esoteric knowledge of spiritual things"; hence, Gnostic referred to those with such knowledge. In coining the term agnostic, Huxley was considering as "Gnostics" a group of his fellow intellectuals—"ists," as he called them—who had eagerly embraced various doctrines or theories that explained the world to their satisfaction. Because he was a "man without a rag of a label to cover himself with," Huxley coined the term agnostic for himself, its first published use being in 1870.