What is time? What is space? What is matter? What is life? What is consciousness? These fundamental questions may seem distinct, even unrelated. However, take a closer look, and you will find that there is an essential unity to Nature. As surprising as it may be, the same patterns are found everywhere. For instance, the lengths of words vary like the lengths of genes; the strengths of earthquakes vary like those of the impulses in the brain. Innovations spread like epidemics. Mollusk shells, flower heads, cyclones, and galaxies spiral in a similar way. Galileo long ago recognized the universality of these patterns, but the reason for them has remained a mystery until now. This Grand Regularity is explained by the fact that everything that exists is made up of the same primary constituents, quanta of light. Through this insight, we find answers to many foundational questions concerning anything from elementary particles to the expanding universe and from the evolution of biotas to the ascent of cultures. This profound view also sheds light on the fate of humankind. Can we question our beliefs? Can we discern the whole? Are we once again heading toward a new worldview? The author Arto Annila, former professor of biophysics at the University of Helsinki, provides plenty of food for thought with scientific realism, spiced up with personal experiences about the reality of science.