Prediction is your brain's primary job title, and it does it all of the time whether you're conscious or not. As an organ your brain actually does many things that include autonomic functions such as breathing (handled in the sympathetic nervous system, rooted in the medulla), to reflexive activity such as the Fight-or-Flight response to environmental threats. But high level thinking revolves around planning for the future to ensure your continued survival against anticipated threats. Your memory, emotions and reasoning abilities all evolved to this end. And while they are not unique to humans, humans do have an extremely advanced capacity for all three compared to other animals.
Each era of human development has its own metaphor for the brain, and today's metaphor is the computer. Today's cognitive scientists have a habit of describing human thought in terms of a computer program, even though it's not accurate. There is an algorithm that does thinking--a procedural series of instructions executed on the hardware of the brain--and if you could discover that algorithm and replicate it on a computer then the computer would think just like a human does. Unfortunately this analogy isn't the truth, but every time we use a metaphor we gain a kind of understanding that eventually leads us to the truth, so for the moment we'll roll with it: the brain is a computer, and your mind is a program working on sensory input, storing and retrieving some of it in the computer's memory.
In these terms, then, intelligent thought is about creating hypotheses and testing theml. Hypotheses are a model of how the world works--a theory--and we test those models by looking for what they predict. If we can't find any evidence of the predictions then we discard the model and move on to another one. All of our behavior as people can be described as the ongoing search for ever more accurate models by imagining them and then testing them.
Hypotheses are the creative act. In art, relationships, mathematics and engineering we invent some kind of idea by combining two ideas into one, a process called synthesis. Even when it feels like an idea has sprung from virgin cloth, if you inspect it deeply enough you'll see that it was actually formed by combining two ideas that we already knew. The creative act is simply in choosing where to tie them together. All ideas are chained to this requirement, and the evidence is in the evolution of our culture: everything we've ever produced can be described in terms of simpler things that came before them. Dragons were lizards with a bird's wings, gryphons were eagles merged with lions, unicorns were horses with horns. Take anything--anything that's a product of human culture--and you'll find at least two ideas tied together. Then fantasies can be mixed with other fantasies, to create ideas that mesh three, four, or more ideas together. Always there is a pairing of one thing with another thing, and the uniqueness is always in how.