barking up trees: guilt in spiritual life

Tonight, I was thinking about the value of guilt in spiritual life. Is there a role in it, after all, and are there certain values to feeling guilt? I think that in Western religions especially, there is a common assumption that guilt has a special value of deterring a person from doing something that can be harmful. In a sense, I believe that this idea comes more from a behaviorist tradition, because it works by means of self-punishment. When I really and truly feel that I am to blame for something that has happened, the force of that belief is so severe and painful that I am deterred from performing the same action again. In that sense, we have sometimes heard the expression, 'you have to feel pain in order to embrace change', or something to that effect. But I also wonder if there are in fact detrimental aspects to guilt as well.
   Guilt seems to speak to a universal belief in the power of punishment, both toward self and others. It's as though one assigns a feeling which is so heavy and so blaming that a person will no longer wish to engage in a certain undesirable behavior. But I sometimes wonder how this dynamic of guilt works in relationships. If I am self-punishing, how does that tendency to punish play out in respect to others? I can look at the converse effect and wonder: if I am simply more tolerant and understanding towards others, would I not also start to feel less guilty and punishing toward myself whenever things don't turn out as I thought they should be? It can perhaps hardly be the case that the guilt one feels toward oneself does not have an effect on others. I believe that feeling inner guilt can set a precedent for how one views the behaviors of others.
   The way out of this impasse is that I can start to slowly appreciate that whatever I have done in the past is not capturing the fullest and deepest parts of my being. This is quite opposite to a strict view of morality where a person tries to apply negative deterrents to prevent her or himself from performing specific actions. This latter view can work in some situations, but the problem is that it doesn't expand the spirit in any way, and it tends to leave a person living in fear of being reprimanded.
   I am really quite convinced that feeling bad about what one has done in the past is not the best idea. The idea would be to use what one has learned from the past to cultivate a wider and more forgiving understanding of all sentient beings.