Have you heard the expression, “That’s a solid thought.”
Well, solid thoughts are nothing more than a joke and a good example of an oxymoron. You try to ‘hold onto’ them, and they are not there. We simply grasp at the memory of them, and sometimes our ideas about them. Thoughts about thoughts, and ideas about thoughts. It is like attempting to freeze smoke. We do not actually freeze smoke, only the particles it is made of. We do not hold onto thoughts, only their impressions and the ideas they generate. Do not hold onto these. They will only create attachments and bondage.
Watch thoughts come and go like smoke.