From my notebook:
In the Tibetan Buddhist path we are asked to pause before any period of meditative practice and precede it with reflection on the preciousness of a human life. This is not because we as humans are superior to other beings, but because we can "change the karma." In other words, graced with self-reflexive consciousness, we are endowed with the capacity for choice -- to take stock of what we are doing and change direction.
~ Joanna Macy, from "Gratitude: Where Healing the Earth Begins", Shambhala Sun, November 2007 issue