INDEX, a word that may be understood either specially as a table of references to a book or, more generally, as an indicator of the position of required information on any given subject. According to classical usage, the Latin word index denoted a discoverer, discloser or informer; a catalogue or list; an inscription; the title of a book; and the fore or index-finger. Cicero also used the word to express the table of contents to a book, and explained his meaning by the Greek form syllabus. Shakespeare uses the word with the general meaning of a table of contents or preface thus Nestor says (Troilus and Cressida, i. 3):
" And in such indexes, although small pricks To their subsequent volumes, there is seen The baby figure of the giant mass."
Table was the usual English word, -and index was not thoroughly naturalized until the beginning of the 17th century, and even then it was usual to explain it as " index or table." By the present English usage, according to which the word " table " is reserved for the summary of the contents as they occur in a book, and the word " index " for the arranged analysis of the contents for the purpose of detailed reference, we obtain an advantage not enjoyed in other languages; for the French table is used for both kinds, as is indice in Italian and Spanish. There is a group of words each of which has its distinct meaning but finds its respective place under the general heading of index work; these are calendar, catalogue, digest, inventory, register, summary, syllabus and table. 1 The value of indexes was recognized in the earliest times, and many old books have full and admirably constructed ones. A good index has sometimes kept a dull book alive by reason of the value or amusing character of its contents. Carlyle referred to Prynne's Histrio-Mastix as " a book still extant, but never more to be read by mortal "; but the index must have given amusement to many from the curious character of its entries, and Attorney-General Noy particularly alluded to it in his speech at Prynne's trial. Indexes have sometimes been used as vehicles of satire, and the witty Dr William King was the first to use them as a weapon of attack. His earliest essay in this field was the index added to the second edition of the Hon. Charles Boyle's attack upon Bentley's Dissertation on the Epistles of Phalaris (169%).
To serve its purpose well, an index to a book must be compiled with care, the references being placed under the heading that the reader is most likely to seek. An index should be one and indivisible, and not broken up into several alphabets; thus every work, whether in one or more volumes, ought to have its complete index. The mode of arrangement calls for special attention; this may be either chronological, alphabetical or according to classes, but great confusion will be caused by uniting the three systems. The alphabetical arrangement is so simple, convenient and easily understood that it has naturally superseded the other forms, save in some exceptional cases. Much of the value of an index depends upon the mode in which it is printed, and every endeavour should be made to set it out with clearness. In old indexes the indexed word was not brought to the front, but was left in its place in the sentence, so that the alphabetical order was not made perceptible to the eye. There are few points in which the printer is more likely to go wrong than in the use of marks of repetition, and many otherwise good indexes are full of the most perplexing cases of misapplication in this respect. The oft-quoted instance, Mill on Liberty on the Floss actually occurred in a catalogue. But in modern times there 1 Another old word occasionally used in the sense of an index is " pye." SirT. Duffus Hardy, in some observations on the derivation of the word " Pye-Book " (which most probably comes from the Latin pica), remarks that the earliest use he had noted of pye in this sense is dated 1547 " a Pye of all the names of such Bahves as been to accompte pro anno regni regis Edwardi Sexti primo."
has been a great advance in the art of indexing, especially since the foundation in 1877 in England of the Index Society; and the growth of great libraries has given a stimulus to this method of making it easy for readers and researchers to find a ready reference to the facts or discussions they require. Not only has it become almost a sine qua non that any good book must have its own index, but the art of indexing has been applied to those books which are really collections of books (such as the Encyclopaedia Britannica) , to a great newspaper like the London Times, and to the cataloguing of great libraries themselves. The work in these more elaborate cases has been enormously facilitated by the modern devices by means of which separate cards are used, arranged in drawers and cases, American enterprise in this direction having led the way. And the value of the work done in this respect by the Congressional Library at Washington, the British Museum and the London Library (notably by its Subject Index published in 1909) cannot well be exaggerated. (See also BIBLIOGRAPHY).
There are numerous books on Indexing, but the best for any one who wants to get a general idea is H. B. Wheatley's How to make an Index (1902).
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)