The period at the end of the first sentence shows that all the words preceding it are to be taken together. Notice the similar use of the other periods.
Notice the semicolon which is used to separate the two clauses of the first sentence. Each clause is complete in itself and might be taken separately; yet they are sufficiently related to be included in one sentence. The semicolon is therefore used to show a slighter separation between the thoughts than would be indicated by the use of the period.
The commas show a still slighter separation, being used to divide the lesser groups of words. Notice this use of the two commas in the first sentence. In the second sentence the commas before and after "heeding nothing of all this" show that these words belong together, and that "But Pandora" belongs to "lifted the lid," etc.
Notice the use of the interrogation point and the exclamation point in the last paragraph.
These various marks, then, are used to help the reader. They show the grammatical structure or grouping. Let us now study these marks in detail, beginning with those that indicate the close of the larger groups,—the period, the exclamation point, the interrogation point.
96. The Period.—The period marks the end of a declarative or imperative sentence.
The period is also used after an abbreviation. (For a list of common abbreviations, see p. 267.)
97. The Question Mark.—The question mark is placed at the end of every direct question. It is not used with an indirect question.
Shall I go?