In his book The Beginning of Infinity: Explanations That Transform the World, David Deutsch makes the following comment "Base metals can be transmuted into gold by stars, and by intelligent beings who understand the processes that power stars, but by nothing else in the universe." I have used this quote many times in lectures and essays because it illustrates what I regard as the most significant property of the universe – that it has given rise to subsystems (in this case human beings) who are not merely able to observe nature (i.e. to create an abbreviated internal representation of it), but to understand it. How has this astonishing ability come into being? Einstein wrote “The eternal mystery of the world is its comprehensibility,” and to me at least, it remains a mystery. The human mind – and by extension what we now call artificial intelligence – are the products of life. Transformations that are impossible on Earth (e.g. gold from base metals) without the activities of comprehending organisms suggest that life should be defined by its ability to navigate from mundane physical states to “impossible” states. Many scientists have proposed that there is a “life principle” at work in nature, coaxing matter into life whenever conditions are favourable. But in my view, what is needed is a comprehensibility principle, built into the fabric of reality (to use another beautiful Deutsch phrase). No such principle is apparent within the currently known laws of nature, and that implies there are new fundamental aspects of reality for a future generation of scientists to uncover. Only then will humans fully grasp the significance of their place in the universe.