Packing for our last camping trip one of my kids saw me put in a flashlight. They went and grabbed another flashlight, brought it to me and said "2 is 1 and 1 is none" proud dad.

I may not need 2 flashlights, 2 knives, 2 radios with spare batteries and so on for this 1 mile hike on a well marked trail I know like the back of my hand with traffic so high I'll never be alone more than 5 minutes, but look at my calves!