The tossed concrete-block salad that is today’s Acayucan recalls the crumbling stone-block ruins of yesterday’s Olmec settlements without the justification of the passing time. Mexicans lack the gringo compulsion to order the world. Still, they often derive greater happiness from that world they feel less need to control, which may partly explain this American’s pursuit of happiness in this disorganized place.

For the ragged shoeless Hondurans who beg in the food market before climbing atop a no...