This is a big topic and the science of feelings/emotions is growing. Here's an article to get us started.
Feelings have a lot of power in our lives. I'm exploring this subject a lot right now, partly because I have a large range of emotions in my work with the dying and partly because I see so many people who are led by the nose by some feeling and they have lost control of their behaviour. Sometimes the consequences of losing control because of our feelings is very serious. More importantly, how can we harness our feelings to improve our lives?