Very recently one of my sons and I put passenger seats back into our family van. We had taken the removable seats out in order to have the space to move some furniture from home to apartment. Now it was time to put the seats back in.
I was wearing my prescription sunglasses on the sunny afternoon when we tackled the task. As we hefted the bulky and heavy rear bench seat into the van, something sharply struck the right lens of my glasses. It was a spring, some part of the mechanism that locks the seats down. Having snapped suddenly, it fired at my face with high velocity. My face was no more than a few inches from the launch point of the spring. From the location of the point of impact, it was clear that the high-speed missile would have struck me squarely in the right eye, had I not had my glasses on.