Reality has a habit of repeating itself in patterns, and once you see the pattern you cannot unsee it. We start with Aristotle’s four causes, then jump forward to a modern fourfold structure in physics: gravity, electromagnetism, the strong interaction, and the weak interaction. From there we follow the same organizing logic through chemistry and biology, all the way into psychology, where the real question becomes how consciousness can flourish. Along the way, one word keeps earning its plac...