Symmetry is found in the visual arts, architecture and design of artefacts since the earliest time. Many natural objects, both organic and inorganic, display symmetry: from microscopic crystals and sub-atomic particles to macro-cosmic galaxies. Today it features strongly in higher mathematics such as Linear and Abstract Algebra, Projective and Fractal Geometry, Algebraic Topology, Graph and Function Theory, etc., and in many other mathematical disciplines such as Quantum Physics, Relativity, String Theory, etc. Most primary geometry curricula around the world introduce the concept of line symmetry fairly early, and sometimes also that of rotational, translational and glide reflective symmetry. However, in high school and even college geometry textbooks, there still tends to be a general lack of use of symmetry, not only to organise and classify geometric objects, but also to explain (prove) more easily, logically, certain properties of these objects as theorems. In this article, the author examines the simplicity of symmetry and presents examples designed to encourage its use more often in high school geometry. (Contains 6 figures and 2 notes.)