Do not fear the arising of negative thoughts.
Fear detecting them too late:
after the word is spoken, the deed committed.
For by then the harm is done.
At some point in our practice, we will reach the level where we, like bodhisattvas, fear causes, not results. But until we reach that level, we work at a lower one where we strive to detect the thought and prevent the action.
An almost instantaneous interaction.
Our thoughts arise with amazing speed and subtlety, and in staggering numbers. The vast majority of them are not even detectable as thoughts by us for they are incredibly slight vibrations. But even the subtlest vibration is a cause that will have a result.
The calmer our mind, the deeper we can go in detecting our thoughts. This is where our cultivation comes in because the sooner we detect our arising thoughts, the better our chances of stopping ourselves from automatically acting upon them, and doing harm.