"To me, literature is something much more alive. More like a barrel of eels. When a writer creates a new eel, it wriggles its way into the barrel, muscles a path into the great teeming mass from which it came in the first place. It's a new eel, but it shares its eelness with all those other eels that are in the barrel or have ever been in the barrel."
The above quotation is from Thomas C. Foster's How To Read Literature Like a Professor—the detail with which he describes the analogy leads me to believe it isn't one whose meaning is well-known or obvious. What is an appropriate expression for describing an environment whose elements are distinct, but closely related and complementary, that needs no explanation?