One of the things I return to again and again is the idea that we don't really know what intelligence is. We don’t really have a definition for it and even beyond that we don't really kind of have an intuitive way we understand it. Albert Einstein said that the true sign of intelligence is not knowledge but imagination. While that is not a definition of intelligence, it is a Litmus Test for intelligence. Is this true? Is Intelligence indicated by imagination and systems that have no imagination cannot be said to be intelligent? If so it would suggest humans are the only intelligent species on this planet because even other intelligent animals don't appear to have imagination in the way that we do. They don't add abstract thoughts that they communicate. They don't write memorable works of fiction and do all the rest that comes with imagination. Not in any sense that we can understand. I think it’s very interesting that in all of the times we have taught animals to communicate with humans like in sign language with apes and whatnot no animal has ever asked a question. Actually there may be one exception to that. There may be a bird, a parrot who asked, “What color am I.” He certainly said that, but there's some evidence to suggest that as he was learning he wanted to know what color he was after seeing himself in a mirror. That might be a tiny kernel of imagination.