I'm looking for a word to describe a virtue or character trait relating to the belief or practice of living in harmony with nature. It should not have any negative or derogatory connotations, nor should it imply any sort of primitiveness as the people in question might well be very technologically advanced.
Natural or naturalness are the best that I have come up with, but they also both seem a little bland and on the nose.
Something like savage or barbaric is closer to what I'm aiming for, but obviously those both have a negative tone which precludes them from being used a virtue for which someone might be praised. Uncivilized is also similar, but would imply the backwardness that I'm trying to avoid also.
Example: The people of Utopia have learned the value of ________, so that, while they have not sacrificed their technological advancement, they have been careful to keep their progress sustainable and to remain conscious of their environment at all times.