PARENTHESIS
537. In our study of the comma and the dash we have found that parenthetical statements are set off from the rest of the sentence sometimes by a comma and sometimes by a dash. When the connection with the rest of the sentence is close, and yet the words are thrown in in a parenthetical way, commas are used to separate the parenthetical statement from the rest of the sentence.
538. When the connection is not quite so close, the dash is used instead of the comma to indicate the fact that this statement is thrown in by way of explanation or additional statement. But when we use explanatory words or parenthetical statements that have little or no connection with the rest of the sentence, these phrases or clauses are separated from the rest of the sentences by the parenthesis.
539. GENERAL RULE:—Marks of parenthesis are used to set off expressions that have no vital connection with the rest of the sentence. For example:
- Ignorance (and why should we hesitate to acknowledge it?) keeps us enslaved.
- Education (and this is a point that needs continual emphasis) is the foundation of all progress.
THE PUNCTUATION OF THE PARENTHESIS
540. If the parenthetical statement asks a question or voices an exclamation, it should be followed by the interrogation point or the exclamation point, within the parenthesis. For example:
- We are all of us (who can deny it?) partial to our own failings.
- The lecturer (and what a marvelous orator he is!) held the audience spellbound for hours.