The orangutans are intrigued by Smits and open up to him in a dialogue of gesture and body language and sounds. And they give him gifts of appreciation for being one of the rare human beings who they know can understand them and communicate with them.

Orangutans are imprisoned by us and the imprisonment is made worse because they know we do not understand them. It is like being forced to stay in a foreign culture where nobody understands your language and your social rules. If someone breaks through that, it can feel liberating and joyful. You naturally feel grateful.

But can orangutans feel grateful?.Why would we assume they can't?

From his sanctuary with his wife and family on the Indonesian island of Sulawasi, Smits this morning went deeper than our past conversations about the development of his consciousness and how that makes orangutans accessible to him.

He talked about the moments of revelation in his life, beginning in an autistic-like state of disassociation and isolation. He was unable to speak until the age of four, when he suddenly grasped the idea of words. At eighteen, a kiss from a young woman revealed a connection to the social world he had been outside.

And then the combination of a lecture about trees and a humble gardener at a university in the Netherlands made clear to him his own gestalt way of understanding of plants and animals.

The achievement of this gestalt connection with the world - and orangutans - is now leading to planning for a research centre on the island of Java that Smits is building with Zimmerman. This is an ambitious project that may someday be a home for a legion of 100 orangutans and people studying the minds of orangutans and communicating with them. Smits even has ideas for orangutans to allow them to communicate with each other through technology like that of Skype.

But how do you fathom the depths of the mind of an orangutan? How do you get beyond the limitations of the abstractions of science?

From the couch on Sulawesi, Smits talked about how a gestalt consciousness - that is, grasping the wholeness of things instantaneously instead of analyzing separate, abstract pieces of information moment by moment - is the bridge of communication between cultures, between us and the natural world, and between us and a thinking, sentient being like an orangutan.

For Smits, an orangutan is driven like him by curiosity to understand the wholeness of life and experience. That is their ingenuity. That is how they make discoveries.

Take, for instance, the female orangutan Laura at the Samboja Lestari project that Smits created on Borneo, where he is creating a tropical forest out of a wasteland with islands for orangutans in centre with moats of water around the islands.

Orangutans can't swim, but somehow Laura crossed the moat to come to the ecolodge that Smits built to visit him.

Laura did that by sounding the depth of the moat with a stick - all of which she hid from the other orangutans - and then crossed the moat where she had measured the water she now knew was not too deep for her.

That is an incredible piece of thinking and problem solving and it is typical of the stories I've heard around the world from zoos and rehabilitation centres for orangutans.

But what really caught my attention this morning was the series of stories that Smits - and his buddy Zimmerman too - told me about the times that orangutans recognized that he was open to them and wanted to communicate with them and understood them.

Sure, orangutans are great traders and will give simple objects to people in exchange for what they want, such as fruit. But these acts with Smits were different and being able to admit that they are different marks a distinction in what different human beings can see in orangutans.

An orangutan named Bruno bit a piece of orange into a circle, wound it in twine he had unwound from burlap, and gave it to Smits. An orangutan in a cage at two in the morning gave the sleepless wanderer Smits an orange she had with her. Another orangutan, Mendu, gave Smits a pit that he passed through the mesh from his lips to those of Smits. All this happened as the result of Smits communing with them. It was an act of recognition and appreciation from one species to another.

Is Smits seeing more deeply into orangutans or indulging his own fantasies? There is obviously going to be disagreement about that among human beings - although maybe not among orangutans.

I repeatedly hear from people with contact with orangutans that you have to see it for yourself and experience it for yourself.

For the ten years I worked on a book about orangutans I was the watcher and the traveller who stayed on the fringe between the conventional world and this world of radical departures into the minds of another species.

But even from the edge I could see the difference in the eyes of an orangutan when it thinks about different things and goes through different moods. And I have seen the difference in the way that orangutans look at people like Willie Smits.

I listened for an hour this morning to Smits talking about all this and then we all felt that the moment had past and we had fallen back into the world again. It felt conventional again, plainer, more familiar, without the energy of the moment before.

Willie wanted to play a Beach Boys song on his guitar. Richard wanted to be on the Internet which feeds him like pure caffeine. I prayed that my voice recorder had caught everything I was already forgetting so quickly, like falling out of a dream when someone knocks on your door.

Willie Smits. Photo by Shawn Thompson