We shall consider these points in this chapter, in order to show (1) the cause of this inconsistency; (2) how, in some measure, it may be avoided; and (3) that much of it is wholly immaterial, being not in the least misleading.
A diagrammatic grouping indicated by the coordinate conjunction and, with or without one of the four principal marks, may help to illustrate the above points and to differentiate, to some extent, the uses of the marks:
| 1. ... | and | ... |
| 2. ... | , and | ... |
| 3. ... | ; and | ... |
| 4. ... | : and | ... |
| 5. ... | . And | ... |
What does the absence of a mark before “and” in Diagram 1, and what does each of the marks in the other diagrams, say to the reader, even before he has seen enough of what follows the conjunction to enable him to apprehend the probable grouping?
We, of course, know that “and” connects words and groups of words which are coördinate in sense, and that such groups are often similar in form. Similarity in form with similarity of relationship in groups of words makes reading easy; and much attention is given to it by good writers.
In Diagram 1 “and” stands between two words or groups of words whose apparent relation is quite unmistakable for their real relation, which was not the case in Sentence 1, which therefore required a mark of punctuation. In other words, no mistake can be made, and therefore no mark is needed. However this diagram may be filled out, “and” joins words or groups of words into a single group, such new group being related to some other word or group in the sentence.
Diagram 2 gives notice of a grouping different from that in Diagram 1; and Diagrams 3, 4, and 5 exhibit still other groupings.
We saw, particularly in Sentences 7, 7-1, and 7-2, a simple grouping which plainly required another and a larger mark than the comma. We saw another kind of grouping in other sentences which also unmistakably required a mark other than the semicolon.
We now come to discuss the basis of differentiating our principal marks, sometimes at points where the choice of a mark is not always unmistakable. In some cases the choice is based upon well-defined sense relations; in other cases it is based upon shades of meaning or upon degrees of separation not sufficiently sharp to make the choice easy, especially under rules for punctuation.