There is a difference between venting anger and expressing it. To vent is simply to blow off steam. Play tennis, hit the wall, scream. Venting may release some tension, but it is far from a complete response to the motion, and it can harm relationships. Anyone in the vicinity of your venting may take it personally and be offended.

To express your anger, on the other hand, is to show your anger about a particular situation or condition. If you are angry at your spouse or partner, hours of workout at the gym are not going to be nearly as effective as letting your partner know how you feel. It may not help to vent, but it may be effective to say, with a degree of passion, what you’re angry about. Afterward, you may have to do a lot of talking, and at a later time go through the process yet again.
One problem with merely venting anger is that the raw emotion may contain memories of many violations and humiliations. You may be angry at many people and for many reasons. To vent this conglomerate of feelings in the presence of a single person is to swamp that person with all your accumulated feelings, most of which have nothing to do with him. Rage turning into violence feels impotent and accomplishes nothing, because you aren’t dealing with the real object of your anger. You are simply giving other people good reason to be angry at you.

A good therapist once told me that you should get angry as many times a day as you visit the bathroom. I think what she meant was, first, that anger is natural. You may not like it, but it has its place and, depending on your temperament, it may be a constant in your life. She also meant that anger arrives on its own schedule and for its own purposes, and its schedule may be different from yours. Finally, she was saying that anger is part of daily life, and you should expect it to appear often….

When you have been done an injustice, anger flares up before you have a chance to understand what has happened. It’s as though someone else is looking out for you and letting you know immediately that you have been wronged. Anger gives you the impetus you need to change conditions that need to be changed. In this way, anger is like a dark guardian angel, a daimonic force – a daimon is an unnamed but felt invisible presence – that offers guidance and spiritual support.
But once this daimonic anger has done its job, you are left with personal decisions. If you don’t act soon, you may forget what gave rise to anger in the first place. The first task is to show your displeasure, and the next might be to examine the situation and ask, “Why am I angry? What exactly has happened?” Anger has content, but if you let it dissipate without reflection and action, it may enter a pool of discontent that swells and stagnates over time. This chronic anger is a corrosive emotion that uglifies everything in its vicinity.

Anger can be so suppressed that you feel a vague discontent, but you don’t even know that the root emotion is anger. You have to bring this core feeling to the surface and see it for what it is. It might help to remember the stories of injustice done to you and to make some headway changing those conditions. It also helps to find a new reason for being angry, for channeling the rage you feel into a cause worthy of your emotion. Notice that in none of these cases do you try to get rid of the anger but rather to give it a strong reason for being.

You need some insight into your anger so that eventually you can deal with its specific focus. Anger is only partly an emotion. It has an intellectual component and helps make sense of your life. If you know precisely what and who angers you, you know where you stand, some of what is going on, and how emotionally to deal with it. Anger sorts out a complex life and constantly restructures it. It may take considerable anger to change jobs or decide on a divorce. It’s obvious that social wrongs are only corrected when the abused get angry enough and resist.

Anger can draw out the knight and warrior in you and transform simple emotion into an effective persona. It can make you a different person. Many men and women going through a dark night describe how they were changed by it, often by becoming more of a warrior. By warrior I don’t mean a violent person, but someone who has taken on an edge and has discovered unknown power. In some cases, simply owning your power, your eccentricity, or your creativity is enough to chase away the mood that has kept you dark and quiet.

If you don’t articulate your angry feelings in some effective way, you may end up turning those feelings against yourself. This is a subtle way of avoiding the anger – by disguising it as self-annoyance. A habit of self-flagellation can lead to a particular dark night of the soul that is centered on a kernel of anger. You block your feeling, choosing this form of depression over the risk of revealing how you actually feel. But anger wants to flow through your system, from your first awareness of injustice to your final syllable of complaint. That feeling of becoming angry may be nothing more or less than the pulse of life asking for expression. The Sufi poet Rumi once wrote:

Don’t use your anger to conceal
a radiance that should not be hidden.

Anger is your spirit flashing out of you. It is your presence on earth insisting upon itself. It can be overdone, of course, be expressed in the wrong ways, and be confused with many other things. But it is still the force of your life, your precious daimon letting itself be known.

-- Thomas Moore, Dark Nights of the Soul

http://www.donshewey.com/2004zine/anger.html