Having dysgraphia, my spelling was (is) pretty bad. Moreover, the nature of dysgraphia is such that I often don’t see spelling errors, as well as other omissions and commissions. Even when my work was proofread—and it always was—when I re-typed my manuscripts, I would correct old errors but I would add just as many new ones.
It was, I think, about 1988, when I got my first computer, and with it a spell checker. I remember when I first learned how to use it. It was one of the happiest moments in my life, and that is not an exaggeration. It seemed like a gift from the gods.
It remains an essential tool. But, as I would learn, it is far, far from perfect. If I substituted words, a common problem with dysgraphics, (like lead for dead) it offers no help. The spell checker’s ability to untangle mangled sentences is, at best, poor. And, it too often is simply wrong, or blind.
So, all honors to those who invented the spell checker. But remember the Third Commandment: Do not worship false gods. Now, professional proofreaders, there is divinity.