“I told the brethren that the Book of Mormon was the most correct of any book on earth, and the keystone of our religion, and a man would get nearer to God by abiding by its precepts, than by any other book.” - Joseph Smith, emphasis added.
That Joseph Smith used the keystone as an analogy to the role the Book of Mormon plays in our religion is fine. But the way Sunday School teachers tend to expound on that analogy is what I take exception with. Here are some points I often hear in Sunday School:
- The keystone bears the weight of the entire arch.
- If you remove the keystone the whole arch will fall.
- You may be able to remove any other piece of the arch, and while it may look crooked, it may still stand.
This is one of those things where it sounds good, but if you stop to think about what you're saying (or hearing), you'll see that the opposite is true for each of these points. We'll take them one at a time.
First, the keystone (D) bears the least weight because it is on the top. In this diagram, the stones labeled C bear the most weight.
Next, if you can imagine quickly removing the keystone (like whipping a tablecloth off a table with plates still on it), one can easily imagine that the two sides of the arch (B stones) would fall toward each other and stop each other's fall. So removing the keystone does not necessarily cause the arch to fall.
Finally, I can't prove this, but imagine pulling out one of the lower B stones. I'm pretty sure there's no safe way (quickly pulling or otherwise) to remove the lower B stones without causing the whole structure to fall.
So what are we left with? Nothing from what I typically hear in Sunday School. I'm sure there are remaining pieces of the keystone analogy that Joseph Smith had in mind when he said it. Perhaps it's that the keystone is at the center of the arch, or that a lot of weight from above the arch rests on the keystone. Who knows?
Here's another point to thinking before you repeat what you hear--especially if you are in a teaching setting.