The measurements of the variation of the resistivity with temperature in increments of 0.02 K for single crystals of YBa2Cu3O6+x by Pomar et al. (Phys. Rev. B 1996-I, 53, 8245−8248) yield discriminating values and show that the resistivity approaches zero at 0 K asymptotically. These measurements, which can serve as a prototype, have been analyzed in terms of equations, generally applicable for any superconductor, that recognize this fact and that describe the conductivities of the normal state with scattering and of the super state for mixed-valent bipolarons having no scattering. These descriptions, together with a description of the diamagnetic transition as a shift in the chemical equilibrium between polarons and bipolarons, identify a rationale for searching for the origin of superconductivity.