Call them the three "i" words.

In my years studying startups and which leadership skills work best, there are three characteristics that separate the good leaders from the great leaders.

A good leader is inspiring, but doesn't seem to have too much knowledge. Someone with vast technical skills forgets how to actually teach people and train them. Someone with amazing teaching skills and encyclopedic knowledge about an industry gets so bogged down in the details, he or she doesn't know how to lead by inspiration.

This is true in life and in business--sometimes, we get hyper-focused on developing one or two skills. Let's say you're creating a company that will make an app that uses artificial intelligence. You do the deep dive and find out about all of the platforms and tools available. You hold countless seminars with your staff so they are up on the latest trends. Yet, your app is one of countless similar apps and lacks ingenuity; your employees sort of yawn about it. Many entrepreneurs are gifted when it comes to company financials (thank you, business school) and people management, or they know how to cut corners to keep the firm afloat, but they fail in the idea-generation department.

Or, let's say you're an idea person. You take your app development team out to the Golden Gate bridge and give each one a freshly-brewed Starbucks, explaining how you plan to take the city of San Francisco by storm (and maybe move on to San Jose at some point). You give them a stump speech about market size and smartphone trends, but then you make a huge blunder by poorly describing some arcane programming technique.

Look no further than the late Steve Jobs for an example of how all three characteristics were on display. No one could argue that Jobs was an idea machine, but those who knew him (and if you see the movie or read the book), you know he was an exceptional communicator. Many of his keynotes at Apple events focused on a succinct, near perfect explanation about why a new product would meet your needs.

Every great leader is a great communicator. Training is an effortless exercise, almost an afterthought. Great leaders distill complex information and make it completely understandable and actionable. You might even say that Jobs could instruct people better than he could inspire them, although they are closely linked. Those who were on the receiving end of the instruction often say they were inspired. (In a few cases, they also felt a bit humiliated, but that's a story for another day.)

But what about being informative? Again, it ties right into being inspirational and instructional. You can't teach and inspire unless you have the knowledge in the first place. I firmly believe one of the reasons Jobs was so successful in his second act at Apple was because he had learned some hard lessons, mostly from being ousted, starting another company that burned out, and by listening to advisers and friends.

You don't go around trumpeting the fact, but every great leader is also a great listener. There's a curiosity about information, and an ability to consume that information and then make it perfectly clear to others. That's why the three words are so important. Without the knowledge and information, without the ability to instruct and train others, you won't really have a chance to inspire them. You'll only lead them so far.