#EssentialVariables

People often interpret *Ashby’s Law* (after W. Ross Ashby) as if the *system*'s internal states must have the ***same level of variety*** as its *environment* in order to survive, which implies that the system should be able to *respond* (react) to every little disturbance from the environment.

This is not completely true because, on the lowest, #regulation, level, the system blocks #variety from an (environmental) #disturbance reaching the (internal, system protected) #EssentialVariables in two ways:

#Passive isolation (sheltering) from most environmental disturbances, and

#Active reaction to (parring with) the remaining disturbance that managed to *break through* this passive protection.

from "Intro to #Cybernetics"
http://pespmc1.vub.ac.be/ASHBBOOK.html