sentences:  He made major contributions to understand the fundamental theory of solids, especially to the behavior of electrons in metals.In a short period, he has contributed profoundly to the concept of quasiparticles and its relation to Fermi liquids, to the dynamics of local systems in metals, to irreversible phenomena in quantum physics.Through his book (N-body problem) and his research, he has established a French school in solid state physics during the last 20 years whose influence extends all over the world.