The technology life cycle, first described by this author in May of 1996 and later discovered (ahem) independently by Gartner as the “technology adoption curve,” has three stages: Hype, disillusionment, and application.

Management trends follow a similar trajectory: Technique, panacea, yesterday’s fad. Which just goes to show that technologists have more sense than management theorists. Technologists finish by finding the useful balance point; management theorists start at the useful balance point and lose it.

Take the notion of “servant leadership.” Introduced by Robert Greenleaf back in 1970 in his book, Servant as Leader, it offered a useful and distinct perspective on how leaders should view their role. Rediscovered by Ken Blanchard and Phil Hodges last year in their book Servant Leader, the concept is rapidly approaching the peak of the panacea phase, a sure sign it’s about to be discarded as last year’s fad.

It’s too bad, too. If you ignore Blanchard and Hodges’ theological spin, there’s value in the idea that leaders are supposed to help, support and develop those they lead.

It isn’t, however, the answer to good leadership. There is no “the” answer. Everything is situational: Sometimes leaders should be servants, providing resources and removing obstacles, just as sometimes they should be posterior-kickers, inspiring visionaries, or politicians adept at herding cats.

The question goes even deeper than the form-follows-function issue of matching style to circumstance. It gets to the heart of why someone chooses to become a leader in the first place.

Some people become leaders because they want to be leaders, which is to say they want power. Everything else is pretext. These are the people most likely to end up in leadership roles, for the simple reason that those who aim at a target are more likely to hit it than those who don’t.

Then there are those described by Greenleaf: They start with the desire to serve, and expand their circle of servitude, as it were. They’re wonderful people, with deep integrity, who tend to get shot at a lot by those who want power for its own sake. The best servant leaders shed their naivete early in their careers, so as to avoid becoming former servant leaders.

A third type of leader — the visionary leader — is, to my way of thinking, the most deserving of the title. These are the people who become leaders because they’re trying to accomplish something. They see a future different from the present, inspire others to see the same possibility, and have the courage, energy, and ability to see both broad strokes and great detail to drive the hard, complex work of making that future a reality. They deserve to be called leaders because others are following them to a destination.

They also deserve to be called dangerous, because a future that’s different from the present is an unknown. That means the risk of unintended consequences. It’s one reason visionary leadership requires courage. It’s also the reason visionary leaders better be good thinkers and better listeners: Most unintended consequences can be avoided through the not-so-simple act of thinking things through. Vision is the focal point for deep thought and hard work and not, as too many self-styled visionaries assert, a substitute for them.

Power-driven leadership, servant leadership and visionary leadership aren’t mutually exclusive alternatives. They’re different dimensions of the character of anyone in a leadership role. To be an effective leader, you need a healthy dose of all three, and others besides.

If you don’t, to some extent, see yourself as the servant of those you lead, they’ll find themselves having to overcome you to achieve the tasks you set out for them. Servant leaders take care of those they lead, help them grow, and clear obstacles out of their paths. Even if you don’t think this is an ethical necessity it’s a good idea if you want those you lead to be as effective as possible.

If you don’t have something important you’re trying to achieve — a vision, for want of a better term — then you’re in the ludicrous position of having no answer when those who follow you ask the question, “Where are we going?” It’s hard, not to mention irritating, to follow someone to nowhere in particular.

And if you don’t, at some level, want authority, that also leads to problems — in particular, to an unwillingness to exert it.

Which is to say that if you don’t want the job, chances are you won’t do it very well.