While a thought is present, look directly at it. See its nature.
It is “thoughts” that have cast us into, and keep us in, samsara. But it is through the recognition of the nature of thoughts that we achieve nirvana. We always have a choice. We can follow thought, be overpowered by it, swept away by it, and when that happens we accumulate karma and we prolong samsara. Or, [we can] simply see the nature of the thought, in which case the thought itself provides an opportunity for insight into the mind’s nature.
Although the nature of our mind, emptiness, is unchanging, the mind can either be overpowered by thoughts, in which case it accumulates karma and perpetuates samsara, or it can see the nature of its own thoughts. Therefore we say: “The discovery of freedom from thought is made within thought.” We cannot discover freedom from the deception of thought by stopping thoughts; we can and must discover it by seeing the nature of thoughts as they arise.
[From a teaching on Little Song to Please the Dakinis by Bardor Tulku Rinpoche. Translated by Lama Yeshe Gyamtso. Full teaching available at the KPL Bookstore.]