Rising just above the horizon, the moon appears larger than it actually is, much larger than when it’s overhead. The colon is like that—abracadabra!—appearing in a way that has a sometimes-magical affect.
Now, it’s true that talk of the colon (of the English variety) is often accompanied by a yawn, a “Ho hum.” But it is geared for many more exciting things than heralding a list (though lists can be exciting), hailing the recipient of a letter or refereeing hours and minutes.
He vied for these things: her attention, her honour, her baked goods, her future.
A sentence builds to what the colon introduces.
He went too far, the die was cast, the verdict rendered: Guilty!
The colon lends importance to what follows it: all eyes here.
It may introduce words that carry great import, or a query or conclusion.
She heard his Oxfords following her, and she spun around, but there was no one: How could he be invisible?
House Style may call for a capital when a question follows (What’s Up Yukon, for instance).
The colon lends dramatic punch to a sentence.
The man packed a satchel, packed a lunch and packed it in because he wasn’t coming back.
The man packed a satchel, packed a lunch and packed it in: he wasn’t coming back.
All that goes before is to prepare us for what follows: he wasn’t coming back.
“:” is the invisible spotlight of the sentence that is quickly and appropriately forgotten in the words that follow it; after all, who was watching Copperfield when the Statue of Liberty disappeared?
The colon may summarize what has gone before.
The magician’s eyes pierced the audience, his voice hypnotic, his hands mesmerizing: we were his captives.
Or, it may be used to form an impression from the sum of our observations.
Beads of perspiration glistened on her forehead and her fingers trembled ever so slightly as she swept away the wayward lock shrouding her vision: she was nervous.
First, a colon weakens surrounding punctuation.
She would not stop searching: invisible or not, she would find him.
She would not stop searching. Invisible or not, she would find him.
Sometimes a sentence needs a full stop, a period.
Second, when everything seems important, nothing is.
The colon should be used creatively and judiciously.