/What is the best way to prevent wrong thoughts from attacking us?/
The thoughts that we have to control are the thoughts that are not productive, the thoughts that are damaging, the thoughts that are destructive, the thoughts that are silly, the thoughts that are negative. These thoughts can come from outside and enter into us; or they may already be inside us and merely come forward. The thoughts that come from outside are easier to control than the thoughts that are already inside. If an undivine thought comes from outside, we have to feel that we have a shield all around us or right in front of us as a protection, especially in front of the forehead. If we feel that our forehead is something vulnerable, delicate, exposed, then we will always be a victim to wrong thoughts. But the moment we consciously make ourselves feel that this forehead is a shield, a solid wall, then wrong thoughts cannot come in.
The thoughts that are already inside us creating problems are more difficult to throw out, but we can do it. We can do it through extension of our consciousness. We have a body, and inside this body are wrong forces that have taken the form of thoughts. What we have to do is extend our physical consciousness through conscious effort and aspiration, as we extend an elastic band, until we feel that our whole body is extended to infinity and has become just a white sheet of infinitely extended consciousness. If we can do this, we will see that our consciousness is all purity.
Each pure thought, each pure drop of consciousness, is like poison to impurity or to wrong thoughts in us. We are afraid of impure thoughts, but impure thoughts are more afraid of our purity.