All of life is a ceaseless mutation: emerging, modifying, disappearing.  The relative constancy of still, centered attention is simply a steady adjustment to the flux of what is observed. Nothing can be relied upon for security.  As soon as you grasp something, it's gone. Anguish emerges from craving for life to be other than it is.  It is the symptom of flight from birth and death, from the pulse of the present.  It is the gnawing mood of unease that haunts the cling to "me" and "mine."

--from, Buddhism Without Beliefs--A Contemporary Guide To Awakening, by Stephen Batchelor