  The evidence for the low mass J^{PC}=0^{++} states is reconsidered. We
suggest classifying the isoscalars f_0(980) and f_0(1500) as members of the
0^{++} nonet, with a mixing rather similar to that of the pseudoscalars \eta'
and \eta. The broad state called f_0(400-1200) or `sigma'' and the state
f_0(1370) are considered as different signals from a single broad resonance,
which we take to be the lowest-lying 0^{++} glueball. The main arguments in
favor of these hypotheses are presented and compared with theoretical
expectations.
