Languages change; they are changing all the time, even as we speak them. This was already known to linguists of the ancient world ‒ such as the phonologists of the period before the Tang dynasty in China, who recognized that the sound patterns of the Chinese syllable were significantly different from what they had been at an earlier time. We usually think of linguistic change first of all in terms of the changing sounds of speech; or, if we consider change in meaning, then it is in terms of the meaning of single words, or small clusters of words that are related. We do not usually think in terms of the meaning potential that characterizes a language as a whole.