Does Having a Killing Thought in the Mind Without Acting on It Violate the Precepts?

In the Hinayana precepts this does not count as breaking the precept: there was no action, the event did not come to completion, no one was killed, so the killing precept is not violated. But according to the Mahayana, it does constitute a violation of the precept, because the mind is the master of all things and also the master of all evils; only when a mental thought arises will subsequent bodily and verbal actions appear. Only when the mind gives rise to a thought of killing does the karma of killing come into being. Therefore, once a thought of killing arises, one has already broken the precept under Mahayana precept discipline, regardless of whether an actual killing took place. Thoughts play the decisive role: thoughts represent the wholesomeness or unwholesomeness of the mind. When a thought arises, karma is created; karmic retribution manifests according to the mind, and birth and death exist according to the mind. Because as soon as a thought arises—before action has yet followed—tathāgatagarbha has already made a record, and in the future tathāgatagarbha will bring about the karmic retribution of wholesome or unwholesome deeds according to that record. If action follows as well, the unwholesome karma is further consolidated, and the retribution becomes even more firmly fixed. True practitioners do not give rise to thoughts casually; if thoughts arise, they are pure thoughts, thoughts of benefiting sentient beings.

The fundamental reason sentient beings violate the precept against killing lies in the mind of anger and the mind of competitiveness. As long as the afflictive mind of anger is subdued, one will not violate the killing precept. Keep away from people and situations that easily give rise to anger, keep away from competitive and contentious environments, do not contend with people, do not contend with circumstances, and subdue the self-centered mind—then basically one will not violate the killing precept.

What deeply taint the mind with anger and ill will are various forms of entertainment and games, in which wars and armed combat are simulated, all involving fighting, killing, bloodshed, and violence. Those who immerse themselves in such games severely pollute their own minds. Immersed in these defilements, they unknowingly come to accept bloodshed and violence, regarding fighting and killing as normal. In the future, when they encounter adverse conditions in real life, they will easily give rise to a contentious mind and may even commit acts of violence.

In the precept sutras the Buddha said that even an imagined killing, with no real person and no real event, is still a violation of the precept, because the mental thought was stirred and the mental action arose, so the seed of unwholesome karma has been stored; when conditions ripen, there will be unwholesome retribution. Mental thoughts determine everything. Only by removing all evil and unwholesome thoughts and being replete with wholesome thoughts can one avoid violating the precepts and creating unwholesome karma, avoid the unwholesome retribution of the three evil destinies, avoid unwholesome retribution within the human realm, and only then can one gradually realize the fruits and escape the birth-and-death cycle of the six destinies of saṃsāra.