The words “page 5” were inserted in the above sentence by the writer himself simply as a matter of direction to the place in the book where the assertion was made. It has no grammatical connection with any part of the sentence: it is simply “thrust in”—it is “parenthetical.” We may modify its strictly parenthetical nature by putting it in another form:
11-1. The author says, on page 5, that he did not go to London.
Here the expression “on page 5” has still the parenthetical nature; but it is given grammatical connection, by means of the preposition “on,” to what precedes it. Thus we call it a “modified parenthesis”; or we may call it “slightly parenthetical” matter. It is obvious that the expression can be omitted in either No. 11 or No. 11-1 without the slightest effect upon the meaning of the sentence.
If we omit the commas in No. 11-1, we give the sentence practically a new meaning; and to complete the meaning a new clause must be added:
11-2. The author says on page 5 that he did not go to London; but he says on page 6 that he did go to London.
In No. 11-2 the language is used in its natural order; and no mark is required in either clause, for each group of words has its natural or logical relation to the group or groups standing next to it. The meaning is unmistakable. But why was the comma used in No. 11-1 and not in No. 11-2? Let us note carefully that we are still dealing with the proper grouping of words and with the relations of group to group, such relations giving rise to real and apparent meanings. With the real meaning of such groups as we are now considering fully understood, we know that a mark is used to change that meaning. Thus, in the consideration of these sentences, we come back to the principle exemplified in Sentences 1 and 2. We use the commas in No. 11-1 because the real meaning of the sentence is not the same as the meaning of the same language in No. 11-2.
One or two illustrative sentences will lead us, gradually and logically, to the punctuation of a large class of sentences in which the groups of words considered have somewhat more definite names than we have given the same groups in the above sentences.
A thorough comprehension of this punctuation is often indispensable, that the writer may convey to the reader his exact meaning, which may depend entirely upon the punctuation,—that is, upon the absence or the presence of marks:
12. Everywhere in America and England, as well as in Germany, the cry for peace is heard.
What does the language of No. 12 mean? Clearly, that in every part (everywhere) of America and in every part of England, as well as in every part of Germany, the cry for peace is heard. That is the apparent, and it is also the real, meaning of the language; but the writer may have had a different meaning in mind. If he did not wish to limit the “cry for peace” to America, England, and Germany, he would have disconnected from “everywhere” these limiting words, writing the sentence thus: