We give the precise correspondence between polarized linear logic and polarized classical logic. The properties of focalization and reversion of linear proofs are at the heart of our analysis: we show that the tq-protocol of normalization for the classical systems LK pol and LK, pol perfectly fits normalization of polarized proof-nets. Some more semantical considerations allow to recover LC as a refinement of multiplicative LK pol. MSC: 03F05; 03F07; 03F52