...his information?

During the whole novel, DOn Corelone is the most informed person of the Corleone Family. Even Tom Hagen who is his auxiliary brain, is not as informed as the Don. This is strange because the Don rarely did something without consulting Hagen.For instance, the Don knew before everybody that Moe Greene has slapped Fredo in Vegas. So I was wondering where Don Corleone got his informations?