Through sustained metacognition we can dig deeply into what thoughts are.
In the same way that feeling hot or cold can be deconstructed into primary input data into conscious experience, thoughts can be deconstructed into patterns of energy.
There is no new thought, only combinations of prior thought plus input from sensory data. So even deeper we can deconstruct that pattern of energy looking at who it came from and what other patterns of energy in the mind combined to form this new one.