People can think on four levels — with feelings, beliefs, facts and ideas. In a perfect world, people would process experience using all four methods. But many people limit themselves to the lower levels, and therefore cannot join the full human adventure.

Here is a description of the levels:

Like so many ideas, it is easy to understand the four levels of human experience, but not understanding them can be risky. If we don't understand this idea, we might become stuck in the lower levels and never even realize the higher levels exist.

For example, there are many people who adopt fixed beliefs early in life, become intellectually lazy and then insist that beliefs are all one needs in life. Some of them even spend their lives desperately trying to convert other people to their belief system, instead of moving on to the higher levels of experience. This is called “arrested development.”

As we advance through the levels of experience, we recapitulate the development of human intelligence itself. At some point our ancestors could only experience emotion, then they possessed beliefs, then they developed true intellect. As individuals, each of us repeats this same development process — but only if we don't get stuck along the way.

We humans can build many wonderful things, but we'll never repeal any of nature's laws. Some people think we have to learn to coexist with nature, but this is wrong — we must learn how to live in nature. And nature is a process of continuous change. The reason we are the most successful species on this planet is not because we are stronger or faster than other animals. We succeed because we can adapt to nature's changes very quickly. We do this with intelligence.

Intelligence is surely the most fantastic creation of nature — it is nature's gift to us. We have the ability to perceive what goes on around us, and more important, we can learn why. We do this with human reason — a process of freeing our minds of old, fixed beliefs and observing reality with an open mind.

Each of us has a choice. We can choose to imitate our ancestors, who could only process reality on the basis of beliefs, or we can ascend to the level of ideas, of reason. If we halt our personal development at the level of beliefs, we cannot contribute to the human adventure — we are condemned to repeat old patterns and then die unnoticed.

If we fail to learn all four levels of human experience, we can still survive for a while on Earth — until nature deals with us as she deals with all inflexible, single-idea species. When looked at in a certain way, the fossil record is the sad story of those creatures that settled on a single idea and hoped nature wouldn't change anything ever again.

The people who ascend to the level of ideas are the same people who will cure diseases, who will colonize Mars, who will lead us into the next chapter of the human adventure. The rest can only be followers.

This is no less than a boot camp for the mind. Please learn the levels of human experience, then experience all of them. The human family — your family — needs you, and you must be properly trained. You must know how to think.