Some writers use commas in the examples given above in preference to semicolons, and usage varies so much among our best writers that it is impossible to lay down a general rule that will be applicable in all cases. If it is desirable to indicate a somewhat close connection between the members of a sentence, a comma should be used; if the connection is slight, it is better to use a semicolon.
THE COLON.
Rule I. Long Sentences.—When the smaller divisions of sentences are separated by semicolons, the main divisions should be separated by a colon.
EXAMPLES.
“Emulation is a dangerous passion to encourage, in some points, in young men; it is so linked with envy: if you reproach your son for not surpassing his school-fellows, he will hate those who are before him.”—Sheridan.
“A man over ninety is a great comfort to all his elderly neighbors: he is a picket-guard at the extreme outpost; and the young folks of sixty and seventy feel that the enemy must get by him before he can come near the camp.”—O. W. Holmes.
Rule II. A Quotation.—A colon should precede a long quotation. If, however, the quotation is short, it is better to use a comma.
EXAMPLES.
Socrates recommended to one of his disciples the following prayer: “O Jupiter, give us those things which are good for us, whether they are such things as we pray for, or such things as we do not pray for; and remove from us those things which are hurtful, though they are such things as we pray for.”