  I bring together evidence for the rapidity with which quasars' radio
synchrotron lobe emission fades and for the intermittency with which jet plasma
is ejected from individual quasars and radio galaxies and affirm the picture
presented by Nipoti et al (2005) that the radio-loudness of quasars is a
function of the epoch at which they are observed. I briefly illustrate this
account with examples of successive episodes of jet activity where the axis
along which jet plasma is launched appears to have precessed. A new model for
the weak core radio emission from radio-quiet quasars, that is not any kind of
jet ejecta, is also briefly described.
