Punctuation: Revealing meaning
From Why We Punctuate by William Livingston Klein and Handbook for Newspaper Workers by Grant Milnor Hyde:
A mark of punctuation is used because it has a meaning and serves a useful purpose in written language.
I. The function of marks is twofold:
A. To reveal the real meaning of written language.
Do not use a punctuation mark unless you see a logical reason for it. Consider each case logically and have a reason for every mark you use. Be ready to defend your usage.
B. To reveal such meaning at a glance.
Punctuation was invented to make writing clear and easy to read. Use marks enough to insure clearness — and no more.
II. Marks perform this function in three ways:
A. By breaking up apparent groups of words, which readily form themselves into new groups.
Marks are used to separate entire sentences; these include the period, the question mark, the exclamation mark, the colon at the end of an introductory sentence, and the quotation mark when concerned with entire sentences.
Now you may go. Come back later.
B. By showing the relations between groups.
Marks are used with individual words, parts of words, or figures; these include certain uses of the colon, certain uses of the period, the uses of the hyphen, the uses of the apostrophe, and some of the uses of quotation marks.
Vegetables are good for you: kale, spinach, carrots, beets.
C. By characterizing a group of words.
Marks are used to separate parts of sentences; these include the comma and semicolon in all their uses and the dash in most of its uses.
Boys, like men, may be courageous for principle's sake.
