After we've been sitting for some time, we may see that our practice naturally flows through a number of different stages. To borrow Kierkegaard's terminology for the different forms of the moral life, we might call them the aesthetic, the ethical, and the religious.
In the aesthetic stage, we are primarily concerned with our private experience of sitting. We might focus on the physical difficulties we have sitting with pain or with the psychological difficulties associated with thoughts that seem to wander and proliferate out of control. Or as we settle into our practice, sitting may become the source of various sorts of pleasure. We might use our sitting to calm or relax our minds, to create a daily oasis of quiet and peace in our lives. Perhaps we even experience moments of intense joy. There's nothing wrong with any of these feelings, of course, it's only that at this stage we're experiencing them in the context of an essentially self-centered practice - a practice pre-occupied with the quality of moment to moment experience. At this stage, even when so-called enlightenment experiences give us a moment of light, instead of using that light to illuminate our life, we become infatuated with its brightness - Zen moths dazzled by our own brilliance.
Kierkegaard calls his next stage the ethical, and here we begin to move out of our self-centeredness and into an awareness of how our actions and reactions effect those around us. We learn to focus not so much on how life is treating us, but how we respond to life. We are attentive to the world around us, and take responsibility for it. We realize practice is not simply something that goes on on our cushions, but is manifested in every moment of our lives. How the zendo is run, how newcomers are treated, how we interact with each other outside the zendo, all those mundane things that, in the first stage, we tended to ignore or treat as a means to an end, now become central to our conception of practice. In this stage, the danger lies in becoming attached to making everything run smoothly and properly. We can be self-consciously aware of our "compassion" or some other attribute of being a "good" Zen student.
The third stage, which Kierkegaard called the religious, is one that he described as exemplified by the story of Abraham's willingness to sacrifice his own son Isaac to the Lord. Here we go beyond any self-centered notion of our own pleasure, beyond our notion of what's good or even rational. Practice demands we give up what we cherish the most. This is the stage where our core beliefs are challenged - those fundamental notions of who we are and what we must do in order to psychologically survive. We face life as it is, and bow to it as our true teacher. The danger at this stage is to become attached to one's own sense of heroic renunciation, the Self making a show of its own sacrifice, and laying the foundation for a new brand of self-centeredness. Extremes of asceticism, flights to the monastery, an impulsive desire to become - and become known as - a monk, all may be self-centered parodies of the truly religious life.
What does it mean to trust in life, to trust our practice? Simply a willingness to let it carry us through all these three stages, which it will inevitably do, each of us in its own way, in its own time. But it is all too easy to become caught up in the various dead-ends and eddies that accompany each stage. That is where an individual teacher comes in - someone who knows us, and knows the pitfalls of practice, and who can help keep us on our path.