From Chapter 3: The Semicolon (The Bridge) -A dash of style by Noah Lukeman
“When a writer is taking pains to write for his reader rather than to impress him,
semicolons can seem like the grammarian’s happiest invention.”
—John Trimble, Writing With Style
Between the comma and the period you’ll find the semicolon. Pausing more strongly than the comma, yet dividing more weakly than the period, it is a mediator. The semicolon does not have as many functions as the comma, yet it has more than the period. As Eric Partridge says in You Have a Point There, “By its very form (;) [the semicolon] betrays its dual nature: it is both period and comma.” As such, it is best thought of as a bridge between two worlds.
The primary function of the semicolon is to connect two complete (thematically similar) sentences, thereby making them one. But when and how to do that is open to interpretation. The semicolon has been overused (Virginia Woolf’s To the Lighthouse) and questionably used (Herman Melville’s Moby Dick) throughout its existence , and has been the subject of endless debate. Compounding the debate is the fact that, grammatically, the semicolon is never necessary; two short sentences can always coexist without being connected. Artistically, though, the semicolon opens a world of possibilities, and can lend a huge impact. In this sense, it is the punctuation mark best suited for creative writers.
The semicolon is a powerful tool in the writer’s arsenal. It is probably the most elegant of all forms of punctuation (it has been dubbed “a compliment from the writer to the reader”), and can offer an excellent solution to balancing sentence length and rhythm. Yet, ironically, it is often overlooked and underused by writers today. So in this chapter we’ll focus on how—and why—to use it. We’ll learn what we gain from its presence, and what we lose when we don’t invite it into the symphony of punctuation.
... to read more - http://www.lukeman.com/adashofstyle/read.htm