  We consider a finite, closed and selfbound many--body system in which a
collective degree of freedom is excited. The redistribution of energy and
momentum into a finite number of the non-collective degrees of freedom is
referred to as spreading as opposed to damping in open systems. Spreading
closely relates to thermalization, but while thermalization requires
non-integrability, spreading can also present in integrable systems. We
identify subtle features which determine the onset of spreading in an
integrable model and compare the result with a non--integrable case.
