Bohr proposed in the framework of complementarity a solution to the well-known difficulty to reconcile the irreversible phenomena with the dynamical reversible laws.His proposal is that the experiences that define the dynamical concepts are mutually exclusive with the experiences that define the thermo dynamical concepts.Bohr did not state precisely the considerations that support his proposition.A critical analysis of Bohr’s suggestionis presented. A thermodynamical indivisibility is also identified which would be manifested through the complementary relation between dynamics and thermodynamics, and that will be present in classical phenomena. This indivisibility is compared to the quantum phenomena’s indivisibility.