Lessons from the fragile

What's the opposite of fragile? Most people's immediate answer is "robust" or "resilient". But consider… if we subject something that is fragile to stress, shock, randomness or volatility, we can expect that it will be harmed. If we do the same to something that is robust or resilient, we can expect that it will resist harm - but won't be any better off than when we started. But what if...