 SSB allows symmetric theories to describe asymmetric reality. In short, SSB provides a way of understanding the complexity of nature without renouncing fundamental symmetries. But why should we prefer symmetric to asymmetric fundamental laws? In other words, why assume that an observed asymmetry requires a cause, which can be an explicit breaking of the symmetry of the laws, asymmetric initial conditions, or SSB? Note that this assumption is very similar to the one expressed by Curie in his famous 1894 paper. Curie’s principle (the symmetries of the causes must be found in the effects; or, equivalently, the asymmetries of the effects must be found in the causes), when extended to include the case of SSB, is equivalent to a methodological principle according to which an asymmetry of the phenomena must come from the breaking (explicit or spontaneous) of the symmetry of the fundamental laws. What the real nature of this principle is remains an open issue, at the centre of a developing debate (see  Section 3,  above).