Without the ability to daydream and hallucinate, computers will never think as humans do. David Gelernter, Yale professor of computer science, predicts the next stages of AI. "As far as we know, there is no way to achieve consciousness on a computer or any collection of computers. However—and this is the interesting (or dangerous) part—the cognitive spectrum, once we understand its operation and fill in the details, is a guide to the construction of simulated or artificial thought. We can build software models of Consciousness and Memory, and then set them in rhythmic motion."