PUNCTUATION is the use of signs to help readers understand and express written matter. It includes things like capital letters, commas, indented first lines of paragraphs, and spaces between words—all the routine devices that help readers decipher prose quickly and accurately. Because the idea of punctuation arose long after the invention of writing itself, ancient texts lack most of the aids to comprehension that we take for granted:
Modern American punctuation is a kind of living history of Western culture. It is composed of practices and innovations developed by ancient writers, medieval monks, Norman conquerors, Renaissance humanists, Enlightenment rationalists, American grammarians, and ordinary speakers of American English. Over time new marks and devices have appeared and changed, and standards of punctuation have changed as well. An 18th-century version of this text, for instance, would seem to us to have far too many commas. Indeed the rules of punctuation, which many people mistake for timeless expressions of pure logic, are better understood as the product of an ongoing tug-of-war between reason, custom, and fickle fashion.
But for students and scholars, appealing to history does little good. Defying today's punctuation rules is perceived by readers as a sign of ignorance or carelessness, two cardinal sins in the academic world. Thus it's prudent to treat the rules of punctuation as if they really were commandments graven in stone. This chapter will consider the essentials of punctuation: the rules and customs governing commas and comma splices, semicolons, colons, dashes, parentheses, and question marks. (We'll deal with the complexities of quotation marks, as well as ellipsis and brackets, in Chapter 6.)
But punctuation is more than an arbitrary system of rules. Its purpose is to help your reader make sense of what you've written. Within the