For want of a horseshoe, the horse was lost.
For want of a horse, the wagon was lost.
For want of a wagon, the supplies were lost.
For want of supplies, the outpost was lost.
For want of an outpost, the expedition was lost.
This is usually read as a parable about the importance of horseshoe nails.
This is incorrect. This is a parable about the importance of safety factors at all levels of one's supply chain.
Crossposted from Dreamwidth (original here), with comments. Comment here or there; comments here will eventually be duplicated to there.