What is "Namo Amida Bu". Namo Amida Bu is the Buddha prayer or nembutsu. "Namo" is the little, vulnerable, conditioned self calling out. "Amida Bu" is the Buddha on the Other Shore calling back. Whenever we conceptualise anything, there is always an "other shore", a beyond.
The act of conceptualising is a mental grasping that emcompasses something and thus puts a boundary upon it. Amida is the boundariless. Beyond the born is the Unborn. Beyond the self is the Measureless. Beyond our frailty is Amida. We have been born - we are here - how can we make sense of it? Human beings seek to make meaning out of their existence. A great meaning cannot be accomplished within oneself, however, but only by going beyond oneself. The religions in the world offer ways to try to conceptualise this "beyond-self" experience. Buddhism does so in a way that does not load us with dogma, guilt, or an undue metaphysical burden. Some metaphysics are an unavoidable dimension of any kind of spiritual reflection, but we should know that metaphysics grows out of the experience of existence. I exist. I see that I am a small and vulnerable being in vital need of help of all kinds. I call out. Namo Amida Bu. I call out to the unknown that lies beyond myself. It is the power that forms and supports me. In order to be a self, one must alienate oneself from the rest of the universe. With Namo Amida Bu we call to our other half - though, of course, the "halves" are disproportionate, since I am virtually nothing and it is everything. So by calling the nembutsu, I recognise my own self assertion: I recognise both the strength and the foolishness of my project to be somebody - and I celebrate the fact that the universe is always calling me back.