One grammar guide tells me Star Trek Capt. James T. Kirk should be reprimanded for splitting an infinitive when he says, "to boldly go where no man has gone before."

Heresy, I say. Would it mean half as much if Kirk had said, "to go boldly where no man has gone before?" Yech.

A split infinitive occurs when a word, usually an adverb, separates the infinitive marker to from the verb (for more on infinitives, click here).

In general, you want to avoid splitting infinitives. But don't go nuts doing it. "Knowing when to split requires a good ear and a keen eye," Garner's Modern American Usage says.

Click on the following examples and you'll see that to flatly reject doesn't convey the same meaning as to reject flatly. Thus, a split is justified to preserve meaning.

Click on these examples to see how splitting an infinitive preserves flow: to always be prepared; to be always prepared.

According to The Cambridge Guide to English Usage, the consensus is: 

• Do NOT split an infinitive if it creates an inelegant sentence.
• Do split an infinitive if it avoids awkward wording, preserves rhythm or achieves the intended meaning or emphasis.