When we explore Nature at distances much smaller than the size of an atom, we find new and mysterious physical principles. At such small sizes, particles are governed by "quantum theory". Quantum theory tells us that some aspects of particle motion cannot be known as a matter of principle. This is a challenge to those of us who would like to do experiments to understand how these particles behave. Fortunately, quantum theory, for all its uncertainty, has its own logic. It predicts patterns in the subatomic world that hold definite information and can be measured to high precision. In this lecture, I will explain how we use these patterns in experiments with high energy particles to learn about the nature of the subnuclear forces and about the structure of the universe.