WHY IS THE PENCIL BLUE?
But the writers discovered they had forgotten how to spell "unnecessary." They couldn't remember whether they needed a serial comma. And what on earth was parallel construction, anyway? The writers found that their books needed editing.
Thus the editors came and marked the paper with a magical instrument, one whose markings would not show on a copy machine—the blue pencil. They corrected the spelling, added the serial comma (because Chicago said so), and made the construction to be parallel. And it was good.
Many years passed. The writers began to use spell-check and to publish their books independently. The blue pencil passed into legend, and few remembered its existence. But the editors remembered, and they pledged to carry on in the tradition of grammatical excellence exemplified by the blue pencil.
"We owe it to each other to tell stories." –Neil Gaiman