Study of Light Scalars in Photon-Photon Collisions, the learned Lessons

After a short review of the nature of light scalar mesons, we dwell on the investigation of the high-statistics Belle data on two-photon productionof light scalar mesons and ascertain that these data allow us to establish their production mechanisms.We show that light scalars are produced in two-photon collisions via four-quark transitions in contrast to the classic P-wave tensor mesons which are produced via two-quark transitions . In particular, we show that the ideal model prediction : = 25 : 9 is excluded by experiment. Thus we get new strong evidence of the four-quark nature of these states.A programme of further investigations is presented.