"So what happened to the comma in this process? Well, between the 16th century and the present day, it became a kind of scary grammatical sheepdog. As we shall shortly see, the comma has so many jobs as a "separator" (punctuation marks are traditionally either "separators" or "terminators") that it tears about on the hillside of language, endlessly organising words into sensible groups and making them stay put: sorting and dividing; circling and herding; and of course darting off with a peremptory "woof" to round up any wayward subordinate clause that makes a futile bolt for semantic freedom." --