The line-by-line editor looks at each sentence analytically, seeing its components and inner workings, using grammatical concepts as a set of tools for detecting and eliminating flaws. If you simply recognize that a sentence sounds bad, you can't necessarily pinpoint and correct what's wrong. Like the driver who knows that the car won't start but has no idea what to look for under the dutifully raised hood, you can only fiddle with this and that in hit-or-miss fashion.
From Line by Line: How to Edit Your Own Writing (see = http://tinyurl.com/n3po8w )
