I found the following little gem in Google’s library of free and out-of-print books yesterday: it is the story of the origin of the words “agnostic” and “agnosticism”, charmingly told by Richard A. Armstrong, in his book, Agnosticism and Theism in the Nineteenth Century (1905):
The story of how he [T.H. Huxley] introduced the words ‘Agnostic’ and ‘Agnosticism’ into the language is known well enough. He became a member of the Metaphysical Society, at whose meetings men of varied schools eminent in the theological, the philosophical, the literary, and the scientific worlds, discussed the very fundamentals of human thought and knowledge […] Professor Clifford and Frederic Harrison, John Morley and Leslie Stephen, John Tyndall and Huxley himself, ever shrewd and alert, formed indeed a goodly company, and must have held discourse fit entertainment for the gods. But Huxley found that almost all of them were ists of some group or other. Every man stood for some profession of belief on unseen things. He, Huxley, stood for none. He was like a fox without a tail. So he invented for himself the title of ‘agnostic.’ He remembered how in the early days of the Church, the schools of the Gnostics were so called because they professed to know just the things which he himself was quite sure that he did not know. So he put the negative prefix to the word, and called himself ‘Agnostic’ precisely because he did not know or think he knew nor even hope that he ever should know these things; a proclamation that he, unlike the rest, Christian or Materialist, in no way supposed himself to ‘have solved the problem of existence.’ ‘ So,’ says he, ‘ I took the earliest opportunity of parading it at our Society, to show that I, too, had a tail, like the other foxes.’ The term took and with extraordinary rapidity penetrated the English language.
Prometheus Unbound 