If you have a lawnmower and the little plastic center breaks on the rear wheel, it will render the machine unusable. We're talking about a little piece of plastic the size of a half dollar that probably costs less than that to make, but without it the mower is as useless as, well, a three-wheeled lawn mower. You don’t think much about the little piece of plastic on the wheel before it breaks and then that’s all you can think about. The bottom line is without this fifty-cent piece of plastic, your mower is sidelined. It’s impossible to mow with only three wheels.
The absence of one tiny, seemingly insignificant part can cripple the whole machine. It's the same way in the ministry. 1 Corinthians 12:12 reminds us, the body is a unit, though it is made up of many parts; and though all its parts are many, they form one body. Every member is vital to the whole.