The phrase 'nature deficit disorder' was coined to name what previous generations had no name for because it had not yet become epidemic: the accumulated cost of a life lived almost entirely inside human-made environments. The animals in the zoo pace their enclosures — Nasreddin noticed they pace the same way certain men do who have not been outside in too long. What we call restlessness is often the body requesting what the schedule has been withholding.
Each step builds on the last.