Major writers develop their own idiosyncratic patterns of usage, patterns which sometimes are said to drive changes in the vocabularies of their later readers (e.g., "to purify the language of the tribe"). Concordances are lists of all words the writer is known to have used, listed in alphabetical order, with each word followed by all instances of the word’s use in the author’s corpus of published works (also listed alphabetically by the works’ first keywords in the title or abbreviation).

        "What madman would do this?," you ask. There really are people out there with the patience for this kind of long, detailed project, but there also are concordance-writing programs out there (e.g.,KWIC [KeyWord In Context] or OCP [Oxford Concordance Program]) which do the job for us once the author’s works have been digitized. But the hand-made concordances usually are more accurate and have fewer irritating false-hits due to transcription errors by scanners and typisssstts. They’re also hard to do with an author whose MSS contain variant spellings of the same words, but the emergence of a standard edition (like the Riverside Chaucer or Vinaver’s Malory) usually means a concordance project can be attempted with some hope of selling the product.  You start with a huge pile of 3x5 cards and a big stack of standard editions, and before you know it, you’re eighty years old. (Or you get your grad students to do it.)

        "So how and why would I use a concordance?," you ask with admirable persistence. Well, when your whole argument turns upon the author’s use of a keyword (like, say, "pyte"?), you can establish parallel instances in which the word was used to set up a case for Chaucer’s special sense of its significance. And you know I wouldn’t be telling you how to do this were there no chance that he did consider it a special word, eh?