from Tsele Natsok Rangdrol:
"Resting one’s mind without fabrication is considered the single key point of the realization of all the countless profound and extensive oral instructions in meditation practice such as Mahamudra, Dzogchen, Lamdrey, Cho, Zhije and so forth. The oral instructions appear in various modes due to the differences in ways of human understanding.
Some meditators regard meditation practice as simply a thought-free state of mind in which all gross and subtle perceptions of the six senses have ceased. This is called straying into a dull state of shamatha.
Some presume stable meditation to be a state of neutral dullness not embraced by mindfulness.
Some regard meditation as complete clarity, smooth bliss or utter voidness and cling to those experiences.
Some chop their meditation into fragments, believing the objective of meditation to be a vacant state of mind between the cessation of one thought and the arising of the next.
Some hold on to such thoughts as, "The mind-nature is dharmakaya! It is empty! It cannot be grasped!" To think, "Everything is devoid of true existence! It is like a magical illusion! It is like space!" and to regard that as the meditation state is to have fallen into the extreme of intellectual assumption.
Some people claim that whatever is thought or whatever occurs is of the nature of meditation. They stray into craziness by falling under the power of ordinary thinking.
Most others regard thinking as a defect and inhibit it. They believe in resting in meditation after controlling what is being thought and tie themselves up in fixated mindfulness or an ascetic state of mind.
In short, the mind may be still, in turmoil as thoughts and disturbing emotions, or tranquil in any of the experiences of bliss, clarity, and nonthought. Knowing how to sustain the spontaneity of innate naturalness directly in whatever occurs, without having to fabricate, reject or change anything is extremely rare."
~ Tsele Natsok Rangdrol, Lamp of Mahamudra