Let us suggest that the reader study the sentence before proceeding with our discussion of it. Let him put the sentence in the form of a question, and apply it to any story he has recently read. What two answers could be given to the question if applied to two stories requiring different answers?
Now let us ask why the comma is used. The answer is simple, for in our study of marks we have had only one reason for using the comma,—namely, to show that an apparent meaning is not the real meaning. If this is the reason for the use of the comma, the reason will be exemplified by a study of the sentence without the comma:
13-1. Ask whether the people in the story develop for better or for worse.
If the meaning of each sentence is not yet clear, let us consider the group of words following the comma in No. 13 as slightly parenthetical (a modified parenthesis). We may go a step further, and treat them as purely parenthetical, putting them in marks of parenthesis and putting the sentence in the interrogative form:
13-2. Do the people in the story develop (for better or for worse)?
Manifestly, the only answer is yes or no.
Why did Dr. van Dyke add these slightly parenthetical and apparently superfluous words (for better or for worse) to his sentence? He added them, primarily, because he knew some, perhaps many, readers might think “develop” means only growth upward (for better), while it is just as essential for the novelist to depict characters that “develop” downward (for worse) as upward.
But what does No. 13-1 mean? If put in the form of a question, what answer can be given? Only “for better” or “for worse.” This changes the meaning of the language. The first sentence (No. 13) asks whether the people in the story are static or dynamic; the second (No. 13-1) assumes that they are dynamic (they develop), and asks in what direction they develop.
Dr. van Dyke’s entire sentence clearly shows the meaning of the part of it we have been considering. The sentence is as follows:
13-3. Ask whether the people in the story develop, for better or for worse, and how far the change is credible and significant.