In 1894 Pierre Curie formulated rules for relations between physical phenomena and their symmetry. The symmetry concept originated in the geometrical study of crystals, which it served as a well-defined concept from the 1830s. Its extension as a rule for all physics was a gradual and slow process in which applications, though often partial, preceded the formulation and clear conceptualization of the rules. Two traditions that involved “interdisciplinary” study were prominent in applying consideration of symmetry to physics. One is a French tradition of physical crystallography that linked crystalline structure and form to their physical, chemical and even biological qualities, which drew back to Haüy, and included Delafosse, Pasteur, Senarmont, and Curie. This tradition (until Curie) employed qualitative argument in deducing physical properties. A mathematical approach characterizes the second tradition of Franz Neumann and his students. During the 1880s two members of this tradition, Minnigerode and Voigt, formulated rules of symmetry and implicitly recognized their significance. Yet, until 1894 both traditions studied only crystalline or other asymmetric matter. Then, Curie, who drew on the two traditions, extended the rules of symmetry to any physical system including fields and forces. Although originated in a specific idealistic ontological context, symmetry served also adherents of molecular materialism and was eventually found most effective for a phenomenological approach, which avoided any commitment to a specific view of nature or causal processes. Therefore, the rule of symmetry resembles the principles of thermodynamics. Its emergence suggests parallels to the history of energy conservation.