Good neighborhoods provide families a lot of protection, but even the best of communities remain vulnerable to the threat of criminals invading their homes. Our human bodies are also vulnerable to foreign invaders such as bacteria, viruses, fungi, and parasites.

A boom in affordable housing in the 1950s was helped by the invention of a distinctive multifunctional piece of equipment: the backhoe. Its strong yet relatively slender articulated arm allowed precise yet rapid placement for digging or lifting. The manipulative device is trim and fast, since hoses transfer power to it from a powerful hydraulic pump within the main chassis.

After 100 years, automobiles still need engine oil, transmission fluid, brake fluid, antifreeze, power-steering fluid, and so on. Wouldn't it be great if just a single multipurpose fluid could be circulated from a central reservoir? Each part would use only the needed properties of the fluid, exclude detrimental properties, and then send it back.

"And Aaron shall bear the names of the children of Israel in the breastplate of judgment upon his heart, when he goeth in unto the holy place, for a memorial before the LORD continually." (Exodus 28:29)