Here's a little experiment.
Picture a baseball diamond. The whole field: three bases and home plate, infield and outfield, the whole deal.
Now imagine that it's your job to go through the field and make sure all of the coins are facing heads up. All of them.
Next, turn every other row so each coin is tails up.
Now, go through and take out any coins that were made before 1996.
Please turn all of the coins so that every profile of Thomas Jefferson is looking toward third base.
Recruit a team of people to help you. Just make sure you're all following the same set of instructions.
Make sure it's absolutely perfect. Don't miss one, or someone might think you are lazy.
They probably won't account for the fact that you've been looking at these nickels for so long that now all you can see in your mind's eye are nickels upon nickels. You eat, sleep, breathe, and dream nickels.
When you are absolutely sure it's as perfect as you can make it, walk away with the knowledge that you can never make any changes ever again.
This is what it's like to edit a book.
Next time you find a typo, picture a baseball field of nickels.