Abstract
The spontaneous breakdown of the chiral symmetry of the QCD Lagrangian ensures that $\pi\pi$ interactions are weak at low energies. How weak depends on the nature of explicit symmetry breaking. Measurements of $K_{e4}$ decays at DA$\Phi$NE will provide a unique insight into this mechanism and test whether the $q{\overline q}$--condensate is large or small.

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