  We report an Eliashberg analysis of the electron dynamics in YBa_2Cu_3O_6.95.
The magnetic resonance at 41 meV couples to charge carriers and defines the
characteristic shape in energy of the scattering rate \tau^{-1}(T,\omega) which
allows us to construct the charge-spin spectral density I^2\chi(\omega,T) at
temperature T. The T dependence of the weight under the resonance peak in
I^2\chi(\omega,T) agrees with experiment as does that of the London penetration
depth and of the microwave conductivity. Als, at T=0 condensation energy, the
fractional oscillator strength in the condensate, and the ratio of gap to
critical temperature agree well with the data.
