6. Do not break sentences in two.
In other words, do not use periods for commas.
I met them on a Cunard liner several years ago. Coming home from Liverpool to New York.
He was an interesting talker. A man who had traveled all over the world, and lived in half a dozen countries.
In both these examples, the first period should be replaced by a comma, and the following word begun with a small letter.
It is permissible to make an emphatic word or expression serve the purpose of a sentence and to punctuate it accordingly:
Again and again he called out. No reply.
The writer must, however, be certain that the emphasis is warranted, and that he will not be suspected of a mere blunder in punctuation.
Rules 3, 4, 5, and 6 cover the most important principles in the punctuation of ordinary sentences; they should be so thoroughly mastered that their application becomes second nature.