Writing Analytically, 6th Edition - Rosenwasser, David & Stephen, Jill [272]
The period [.] marks the end of a sentence. Make sure what precedes it is an independent clause, that is, a subject plus verb that can stand alone.
The period says to a reader, “This is the end of this particular statement. I’m a mark of closure.”
Example: Lennon rules.
The comma [,] separates the main (independent) clause from dependent elements that modify the main clause. It also separates two main clauses joined by a conjunction—known as a compound sentence. Information that is not central to the main clause is set off in a comma sandwich. The comma does not signify a pause.
The comma says to the reader, “Here is where the main clause begins (or ends),” or “Here is a break in the main clause.” In the case of compound sentences (containing two or more independent clauses), the comma says, “Here is where one main clause ends, and after the conjunction that follows me, another main clause begins.”
Examples: Lennon rules, and McCartney is cute.
Lennon rules, although McCartney is arguably more tuneful.
The semicolon [;] separates two independent clauses not joined by a conjunction. Secondarily, the semicolon can separate two independent clauses joined by a conjunction if either of the clauses already contains commas. In either case, the semicolon both shows a close relationship between the two independent clauses that it connects and distinguishes where one ends and the other begins. It is also the easiest way to fix comma splices (see BWE 2 later in this chapter).
The semicolon says to the reader, “What precedes and what follows me are conceptually close but grammatically independent and thus equal statements.”
Example: Lennon’s lyrics show deep sympathy for the legions of “Nowhere Men” who inhabit the “Strawberry Fields” of their imaginations; McCartney’s lyrics, on the other hand, are more upbeat, forever bidding “Good Day, Sunshine” to the world at large and “Michelle” in particular.
The colon [:] marks the end of a setup for something coming next. It provides a frame, pointing beyond itself, like a spotlight. The colon is quite dramatic, and unlike the semicolon, it links what precedes and follows it formally and tightly rather than loosely and associatively. It usually operates with dramatic force. It can frame a list to follow, separate cause and effect, or divide a brief claim from a more expanded version of the claim. The language on at least one side of the colon must be an independent clause, though both sides can be.
The colon says to the reader, “Concentrate on what follows me for a more detailed explanation of what preceded me” or “What follows me is logically bound with what preceded me.”
Examples: Rubber Soul marked a change in The Beatles’ song-writing: the sentimentality of earlier efforts gave way to a new complexity, both in the range of their subjects and the sophistication of their poetic devices.
Nowhere is this change more evident than in a sequence of songs near the album’s end: “I’m Looking Through You,” “In My Life,” “Wait,” and “If I Needed Someone.”
The dash [—] provides an informal alternative to the colon for adding information to a sentence. Its effect is sudden, of the moment—what springs up impulsively to disrupt and extend in some new way the ongoing train of thought. A pair of dashes provides an invaluable resource to writers for inserting information within a sentence. In this usage, the rule is that the sentence must read coherently if the inserted information is left out. (To type a dash, type two hyphens with no space between, before, or after. This distinguishes the dash from a hyphen [-], which is the mark used for connecting two words into one.)
The dash says to the reader, “This too!” or, in the case of a pair of them, “Remember the thought in the beginning of this sentence because we’re jumping to something else before we come back to finish that thought.”
Examples: For all their loveliness, the songs on Rubber Soul are