The process that is central to the development of language is the critical encounter between different groups (marked by their "physical, cognitive, neurological differences," as NeMLA's note on "resilience" suggests) in possession of different kinds of valuation in the course of which "certain words, tones, rhythms, meanings are offered, felt for, tested, confirmed, asserted, qualified, changed" (Keywords 12). This process of evolution/metamorphosis, as demonstrated by Raymond Williams in his Keywords,  is often accelerated in periods of unprecedented crisis.