25. I purchased the following articles: one dozen pens, one ream of paper, and one box of envelopes.
25-1. The speaker arose, and addressed the audience as follows:
“The occasion which brings us together,” etc.
25-2. The speaker said: “The occasion which brings us together,” etc.
It is difficult to find a reason for this use of the colon, inasmuch as what follows the colon in any of the above sentences, is not a “limb” of the sentence. The relation in No. 25 is clearly that of apposition; and it is the same in Nos. 25-1 and 25-2. In the latter the apposition is between some word not expressed, but understood, and what follows,—for example, “addressed the audience in language such as follows,” “the speaker said these things.”
We have called this the “conventional” use because it has become the accepted punctuation. We introduce it here in order to show that this same relation (apposition) governs in a frequent use of this mark which is not explained by the writers on punctuation.
Before passing to this use of the colon, let us make sure that the meaning of “formal introduction” is quite clear to us. It means that the matter following the colon is announced or suggested in a manner somewhat similar to the announcement made in the words viz., as follows, etc. It thus implies that the matter is introduced according to a form. “He said,” followed by a colon, is one of the usual conventional forms; but he said that is not so considered, and no mark at all follows “said.”
We use a colon throughout this work at the end of the line preceding an example if the example illustrates what precedes. This use of the colon ties the example to what precedes. See the colon preceding Sentence 25, above.
It is also to be noted that the colon loses, in this formal and conventional use, its relative value, that is, its rank above the comma and the semicolon. Thus it often appears in only one or in both of the semicolon-divided groups of a sentence:
25-3. In a bill of exchange there are three original parties: drawer, drawee, and payee; in a promissory note, only two parties: the maker and the payee.
Here we see that the colons are used to group each one of the two parts into which the sentence is divided by a semicolon. We shall show later (Sentence 33) what we consider a much better mode of punctuating such sentences, and thus avoiding the appearance of making the colon subordinate to the semicolon.
We are here seeking to exhibit the relation of apposition. When words or groups of words stand in this relation, the second word or group expresses in another form what is expressed in the first word or group of words. In No. 25 what follows the colon is the same as “articles,” which precedes it. If the word “articles” were omitted, the colon would still be used, “articles” or a like word being understood, as some word is understood in Nos. 25-1 and 25-2. The same relation is shown in Sentence 32-2 by means of parentheses.