You've probably heard this before: I came across it in A Wind in the Door.
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
I had some thoughts.
1. First, the progression is important here. Sometimes a seemingly insignificant item has a giant effect right away, with no intermediary steps--for example, a peanut would, if Serena Williams happened to eat it. (Serena Williams is allergic to peanuts. I Googled "famous people allergic to peanuts" to finish this example. The Internet is wonderful.) So the point the saying is trying to get across isn't merely that seemingly insignificant things can play dramatic roles. It's a more Butterfly-effect statement: a tiny mishap at one end of the chain causes a huge mishap at the other end.
2. The fact that the horseshoe nail played such a crucial role had a whole lot to do with the fact that the nail was in the shoe of a horse being ridden by a messenger to a battle. Horseshoe nails get lost all the time without having dire consequences. This seems like a really Scrooge-ish thing for me to say; it seems as if I'm stomping all over the message of the saying as it was used in A Wind in the Door, which was to say, "No one is insignificant; your role in the universe is important." I'm not, though: I agree with both those statements, resoundingly. What I'm criticizing the metaphor as a vehicle for conveying that message--because, as I say, not all nails are in the shoes of a warhorse carrying a mission-critical messenger. That nail was important in that way, but what about all the rest of us nails? There are three directions we can go:
3a. "They also serve who only stand and wait." This direction asks us to consider what it means for a life to be of consequence. It's not all about the battles! It's also about churning the butter--or about recording the rate of glacial melting, or about saying something friendly to the kid sitting by himself, staring blankly at the wall while his classmates goof off and have fun. Or about standing and waiting. When people resist this direction, sometimes it's that they don't value these other things, but often it's that they don't want to be denied access to traditional realms of glory, and I totally get that.
3b. The Butterfly Effect again, but more roundabout than the messenger's horse going lame because it lost a shoe. Each of us, in our humble nail-ness, may have dramatic effects on events, but in ways that not at all apparent or predictable. You make a joke to your co-worker at the café; a customer overhears it and thinks it's funny; he tells it to his boss, who tells it to her boss, who, spirits lifted by the well-timed humor, goes into highly sensitive diplomatic negotiations in a better frame of mind. Even that's too linear, but you get the idea.
(source is deponti's Flickr, here)
3c. Inherent worth, apart from actions or consequences. This says that nails are a wonder just in their nail-ness, regardless of whether they're holding horse shoes on or hanging pictures to a wall. You are, so you have worth, period.
All three of these things are true, but all three of them are dissatisfying for various reasons. And yet true. For that matter, "For want of a nail" is true too--it just has its limitations if you go teasing it and pulling at its threads. It's almost as if this stuff is complicated and no one formulation is completely satisfying, and yet each has something powerful to say. Hmmmm.