NOT—BUT
The punctuation of intermediate groups of words gives rise to a peculiar phraseology, which needs explanation. We have seen that the intermediate group is set off by commas to show that the sense is suspended at the point where the first comma is placed, to be continued by connection with what follows the complementary comma. We illustrated this process diagrammatically in Sentence 4-3 by actually suspending on the printed page the intermediate group.
We do not hesitate to use commas in the following sentence:
85. His success was attained, not by ability and enterprise, but by friendly assistance.
If we suspend or omit the intermediate group in the above we obtain a result which is not a good sentence:
85-1. His success was attained but by friendly assistance.
We can say of such language as that of No. 85 only that it is idiomatic, thus justifying it as we justify the grammatical solecism “than whom.”
Mr. Wilson makes an exception to this mode of punctuation that is very perplexing; and it is probably because of this that few, if any, other writers refer to or deal with it.
We shall not attempt to discuss Mr. Wilson’s rule, but let us consider one of his examples:
86. It is not from wild beasts, but from untamed passions, that the greatest evils arise to human society.
We think the omission of a comma after “is,” thus suspending the negative group beginning with “not,” is justified, if at all, by the fact that such a sentence is usually read without a pause after the verb; in other words, the language thus readily groups itself, and shows the meaning and the force of the negative intermediate group.
Not a few good writers use a comma before “not” in sentences like No. 86.
If one or more words intervene between the verb and the negative particle, the parts of the sentence do not coalesce, and the comma is required.
87. He came not to teach, but to be taught.
87-1. He came here, not to teach, but to be taught.
If we change the form of No. 87, we may perhaps see somewhat more clearly why this grouping is more natural than would be a grouping made by a comma after the verb (came):
87-2. He did not come to teach, but to be taught.
No. 87-2 seems to show that the grouping made by the comma in No. 87 is a natural grouping.
In spite of Mr. Wilson’s rule, and of our reasoning to explain it, we believe that each mode of punctuating the following sentence is correct, each depending upon where the emphasis is to be laid:
88. The book’s primary aim is, not to convince the skeptic, but to solve the difficulties of the best-thinking men.
88-1. The book’s primary aim is not to convince the skeptic, but to solve the difficulties of the best-thinking men.
In No. 88 the emphasis is placed upon “to solve the difficulties,” the preceding group being thrown in for contrast, thus heightening the effect of the statement made in the next group of words.
In No. 88-1 the emphasis falls upon “not to convince the skeptic,” just as it would if written, “It is not the book’s aim to convince the skeptic.”
Let us note carefully that the mode of punctuation in each of the two preceding sentences would grow out of the context, which would clearly tell where the emphasis was to be laid.
We have dwelt upon this punctuation in order to emphasize a purpose of punctuation too often overlooked.