  Various ways of determining the absolute neutrino masses are briefly reviewed
and their sensitivities compared. The apparent tension between the announced
but unconfirmed observation of the $0\nu\beta\beta$ decay and the neutrino mass
upper limit based on observational cosmology is used as an example of what
could happen eventually. The possibility of a ``nonstandard'' mechanism of the
$0\nu\beta\beta$ decay is stressed and the ways of deciding which of the
possible mechanisms is actually operational are described. The importance of
the $0\nu\beta\beta$ nuclear matrix elements is discussed and their uncertainty
estimated.
