The dugout in the weeds or leaves beneath a backyard willow, the rivulet of a seasonal creek, even the ditch between the front yard and the road-all of these places are entire universes to a young child.

Numerous studies document the benefits to students from school grounds that are ecologically diverse and include free play areas, habitats for wildlife, walking trails, and gardens.

Rather than accepting the drifting separation of the generations, we might begin to define a more complex and interesting set of life stages and parenting passages, each emphasizing the connections to the generations ahead and behind. As I grow older, for example, I might first see my role as a parent in need of older, mentoring parents, and then become a mentoring parent myself. When I become a grandparent, I might expect to seek out older mentoring grandparents, and then later become a mentoring grandparent.

The times I spent with my children in nature are among my most meaningful memories-and I hope theirs.

It takes time--loose, unstructured dreamtime-- to experience nature in a meaningful way. Unless parents are vigilant, such time becomes a scarce resource, not because we intend it to shrink, but because time is consumed by multiple, invisible forces; because our culture currently places so little value on natural play.

Now, my tree-climbing days long behind me, I often think about the lasting value of those early, deliciously idle days. I have come to appreciate the long view afforded by those treetops. The woods were my Ritalin. Nature calmed me, focused me, and yet excited my senses.

Green exercise improves psychological health.