Some excerpts from a great Dzogchen practice book (which I highly recommend: 'The Cycle of Day and Night', which is about integrating the practice from waking to sleep) by a great Dzogchen master, Chogyal Namkhai Norbu Rinpoche.
"(5) The first of the three topics is understanding the practice. "Understanding" (rtogs-pa) is not just reasoning (brtag-pa) and analyzing (dpyad-pa), but it relies upon transmission. Our view (lta-ba) is a way of seeing or looking at things and it may include analysis and explanation. But "understanding" is fundamentally an entering into a knowledge of that view experientially. When we have no concrete knowledge of this sort, we are dependent upon the descriptions and interpretations of others, and these may change from day to day. Without real knowledge, all phenomena (chos kun) are merely false images (bden-med gzugs-brnyan); they do not exist in a real sense, but are like so many reflections in a mirror. A kitten, not knowing the image in the mirror is his own reflection, pursues it as if it were a real playmate. In Dzogchen, all appearances (snang-ba) are understood to be the potency (rtsal) of the energy of the Bodhicitta or the primordial state. These appearances are the qualifications or ornaments of that state. When we enter into knowledge we have no doubt of this. Thus we may conclusively determine (kho-thag-chod) that appearances are a magical display of the mind (sems kyi cho-'phrul).
(6) The Nature of the Mind (sems-nyid) is from the very beginning void or empty (stong-pa) and without any self or concrete substance (bdag-med). But we should not think of mind as being a mere nothing (med-pa) because it has the clarity and limpidity of the mirror. This clarity (gsal-cha) exists unobstructedly and without interruption ('gags-med), just as the moon is reflected in the water in various ways. Thoughts arising in mind are the way in which the Nature of Mind manifests itself. But just as we must understand the reflections in order to understand the nature of the mirror, so we must examine thoughts to see where they arise, where they abide, and where they go. However, when we look into this matter, we discover that there is no place where thoughts arise or abide or go. Nothing can be affirmed and what we find is void or emptiness (stong-pa nyid). This is the real character of the mind. Now, even though this may be the case, thoughts (rnam-rtog) continue to arise without interruption ('gags-med). Therefore, what we find is a primal awareness of pure presence (rig-pa'i ye-shes) where there is no duality of emptiness (stong-pa nyid) on the one hand and clarity (gsal-ba) on the other. This primal awareness is natural and spontaneously self-perfected (rang-bzhin lhun-grub). At the level of mind (sems) we do not find this nonduality because mind operates in time, while the state of pure presence (rig-pa) lies beyond the limits of mind.
(7) When we recognize that appearances are mere ornaments of the real condition of existence (chos nyid rgyan), these appearances which arise to our alertly relaxed (lhug-pa) six senses are self-liberated into their own condition (rang sar grol) whenever they arise. The six sense aggregates (tshogs drug) are the five senses plus the mind (yid). The presence of appearances prior to forming any conception or judgment is called "clarity." Appearances (snang-ba) refer to the external world, whereas the passions or afflictions (non-mongs) and the karmic traces (bag-chags) refer to the world of inner experience. The manifestation of the internal state of pure presence is primal awareness (ye-shes). The arising of pure presence (rig-pa) never lacks in spontaneous self-perfection (lhun-grub), that is to say, its essential qualities, just as the rising sun does not lack its rays. Our passions only grow powerful because we are ignorant of the state of pure presence, and so consequently we follow after our passions. But when we find ourselves in the state of the pure presence of the passions, they do not dominate us nor do we have to suppress them because they are like the ornaments of our primordial state. Thus our passions are self-liberated into their own condition (rang sar grol) whenever they arise.
(8) Appearances and pure presence are inseparable (snang rig dbyer-med). When we recognize (ngos zin) this and find ourselves in this state, then the discursive thoughts arising which grasp at the duality (gnyis su 'dzin-pa'i rnam-rtog) of subject and object, are liberated into their own condition (rang sar grol). We do not try to block or reject them in any way, but we simply remain aware in the presence of their arising. There are three procedures for self-liberation in this case, depending upon the capacity of the practitioner: 1. self-liberation through bare attention (gcer grol), 2. self-liberation upon the arising of a thought (shar grol), and 3. self-liberation as such (rang grol). The term gcer means "bare or naked attention." But this is not yet real self-liberation because, in observing ourselves, we are still applying some degree of effort. For example, when a thought arises, we look it straight in the face and it liberates into its own condition. The term shar means "to arise." At the moment the thought arise, we do not have to make the effort to look it straight in the face, but just as it arises, we find ourselves in the state of presence which is Rig-pa and it self-liberates. True self-liberation (rang-grol) occurs when this capacity is fully developed. At this level, we have arrived at the continuity of the state of Rig-pa.
(9) This verse gives the essence of the matter. The awareness (shes-pa) arising at the first sudden instant (thol-'byung skad-cig dang-po) of sense contact is that pure presence (rig-pa) which is manifested without modification or correction (ma bcos) by the mind and which is not created or produced (skye-med) by any causes. What is this state of presence? It is a condition of existence (de-bzhin-nyid) transcending the limitations of both subject and object (gzung 'dzin mtha' las 'das-pa); it is a natural and authentic (gnyug-ma) self-originated primordial awareness of pure presence (rang-byung rig-pa'i ye-shes). The term de-bzhin-nyid indicates the state characterized by both primordial purity (ka-dag) and spontaneous self-perfection (lhun-grub)."