At times thousands of thoughts arise yet they do not leave a lasting impression in the mind. At other times, only an irrelevant thought arises, yet it leaves a strong impression in the mind. What can be the reason for this? How can one eliminate such disturbing thoughts?
In the word of god:-
The reason is influence of traits of good quality. Thoughts occurring when unconciosusness and ignorance is predominant is a state similar to that of deep sleep. Therefore, those thoughts do not leave a lasting impression in mind.
When quality of goodness prevails which is characterized by detatchemnet towards the world a person experiences the state of awareness. Therefore any disturbing thoughts occurring at that time are vanished by thinking and those thoughts do not leave a lasting impression either.
However, when the quality of passion is prevalent characterised by desires for worldly it leaves a lasting impression on mind.
Therefore the reason some thoughts do leave a lasting impression in mind while others do not, is due to the prevelance of different qualities.
If one examines these thoughts when they arise one will be able to recognise which quality is predominant at that particular time.
However subtle thoughts that arise repeatedly from moment to moment cannot be grasped by anyone. At the most some may be able to distinguish two, three, or four of the most superficial thoughts that arise during the course of the day.