Reading a tweet by @mattbarcomb led me to this post: "Enabling constraints are about opening possibilities by limiting choices". A short read. Coderetreat facilitators use this, and have fun doing it!
Also, "Constraints that Enable Innovation" - Alicia Juarrero, Professor Emerita of Philosophy at Prince George’s Community College (MD) on "enabling" innovation. Overflowing with great stuff on the fundamentals of natural learning.
"Take the system far from equilibrium. Nothing interesting ever happens at equilibrium."
Texas version: "There's Nothing in the Middle of the Road but Yellow Stripes and Dead Armadillos." I'll leave the sourcing as an excise for the reader.