Terry Lee Goodwin appeals from the denial of his extraordinary motion for new trial. His conviction for murder and the death sentence were affirmed by this court in 236 Ga. 339 (223 SE2d 703) (1976).

In his extraordinary motion for new trial the appellant alleged that the trial judge erred in failing to charge the jury on the mitigating circumstances.

It is well settled that errors in a charge are matters which could and should have been raised in the motion for new trial and on appeal. The law is clear that any errors which could have been discovered through the exercise of proper diligence cannot form the basis for an extraordinary motion for new trial. Patterson v. State, 228 Ga. 389 (185 SE2d 762) (1971); Bishop v. State, 117 Ga. App. 93 (2) (159 SE2d 477) (1967); and Barfield v. McEntyre, 136 Ga. App. 294 (221 SE2d 58) (1975). Evidence of mitigating circumstances was developed on the trial of the case and was known to counsel at the time of the first appeal. Any deficiency in the charge in this regard should have been enumerated in that appeal.