firewns said: “Lal, I agree that at least initially it is not possible to control what kind of cetasikas arise as the cittas arise so rapidly. However can kamma beeja be altered, or if not, at least have its effects modified by other kamma beeja?”
It is not that kamma beeja need to be altered. They are unable to bring vipaka (especially in rebirth) when panna is cultivated.
– For example, when one attains the Sotapanna stage, all kamma beeja that can bring in rebirth in the apayas become ineffective. No kamma beeja can bring rebirth once the Arahant stage is attained.
However, kamma vipaka can bring in results for humans until the Arahant’s physical body dies. This has to do with the mental body from being shielded by the physical body. But if a brahma attains the Arahanthood, that brahma will immediately attain Parinibbana, because a brahma does not have a physical body.
This is why Angulimala, who killed 999 people was able to attain the Arahanthood. He did not grasp a new birth at the death of the physical body. But he was subjected to harassment until his death.