  We present new clues to the problem of the radio loudness dichotomy arising
from an extensive search for intranight optical variability in seven sets of
optically luminous radio-quiet quasars and (radio-loud) BL Lacertae objects,
which are matched in optical luminosity and redshift. Our monitoring of
radio-quiet quasars has for the first time clearly detected such intranight
variability, with peak-to-peak amplitudes ~1%, occurring with a duty cycle of ~
1/6. The matched BL Lacs have both higher variability amplitudes and duty
cycles when observed in the same fashion. We show that the much less pronounced
intranight variability of the radio-quiet quasars relative to BL Lacs can be
understood in terms of a modest misalignment of the jets in radio-quiet quasars
from the line-of-sight. We thus infer that relativistic particle jets may well
also emerge from radio-quiet quasars, but while traversing the short
optical-emitting distances, they could be snuffed out, possibly through inverse
Compton losses in the nuclear region.
