The influence of density waves in the solar nebula on the dynamics of a planetesimal disc is discussed. Disc tides are compared to other mechanisms traditionally included in accretion modeling, i.e., gravitational scattering, collisions, and aerodynamic drag. It is argued that density waves become the dominant damping mechanism of dispersion velocities in a disc composed of runaway planetesimals and control its equilibrium state. Resulting dispersion velocities tend to scale with the sound speed instead of the planetesimal escape velocity. Some implications for the mode and time scale of end-stage accretion are also mentioned.