  Kondo temperature is standardly defined from the local zero-temperature
susceptibility in the regime of strong electron correlations as a new scale
controlling the low-temperature asymptotics of thermodynamic quantities. We
show by using a two-particle self-consistent theory that the Kondo temperature
can be identified as a crossover temperature at which the zero-temperature
quantum fluctuations equal the thermal ones in the electron-hole correlation
function. The high-temperature Curie-Weiss susceptibility is shown to go over
to the Pauli one below the Kondo temperature.
