Says Lama Zopa Rinpoche:
It is important to appreciate why the perfection of wisdom teachings are the essence, the heart, of the Buddha’s 84,000 teachings. By showing the ultimate nature of phenomena—emptiness—they reveal the purpose of the Buddha’s descending to this world: to benefit sentient beings. But exactly how does the Buddha do this? He does so by liberating us from the oceans of saṃsāric suffering, which we find unbearable and from which we seek freedom. He descends to liberate us not just from the suffering of pain, but also from the suffering of change, which we regard as temporary saṃsāric pleasure. More than that, he frees us from the pervasive compounded suffering that is the basis of the other two types of suffering.
The Buddha does not liberate us by washing away the negative karma as water might wash our body. Nor is it like removing by hand a thorn that has entered our flesh. Nor is it by transplanting the Buddha’s realizations into us as one might replace a human heart or brain with another human organ or even that of a monkey. How does the Buddha liberate us sentient beings? It is by revealing the truth.
So what is that truth? It is the revealing of the path that, when actualized, ceases all the oceans of saṃsāric suffering together with its causes—delusion and karma. The most essential path for doing this is the perfection of wisdom, the wisdom gone beyond, the wisdom realizing emptiness and, more particularly again, the wisdom directly perceiving emptiness, as this is the one that directly removes and ceases the delusions. Compassion, loving kindness and bodhicitta by themselves alone cannot achieve this goal. Yet, combined with the wisdom directly realizing emptiness, they do assist. Just as one requires a big fund to accomplish a big project, to accomplish the cessation of the subtle defilements and transform one’s mind into the omniscient mind of a buddha requires inconceivably extensive merit. Compassion, loving kindness and bodhicitta help in its accumulation. But the real, actual, or ultimate cause of ceasing the gross and subtle defilements is the wisdom directly perceiving emptiness. This is why the Prajñāpāramitā teachings are the heart of the Buddha’s 84,000 teachings.
 This is an encapsulated reference to the three kinds of suffering epitomizing the first noble truth—the truth of suffering. See the Dalai Lama, Kindness, Clarity, and Insight (Ithaca: Snow Lion, 1984), 21–25. Tegchok glosses the meaning of all-pervasive compounded suffering (khyab pa ’du byed kyi sdug bsngal): “The third kind of duhkha is called the pervasive duhkha of conditioning. This refers to having a body and mind under the control of afflictions and karma. Our physical body, the form aggregate, is conditioned by afflictions and karma. The same is true of our four mental aggregates—feeling, discrimination, volitional factors, and consciousness. This duhkha is called ‘pervasive’ because we have it wherever we are born in cyclic existence, without choice. It is called ‘conditioned’ because it is conditioned by afflictions and karma; it is under their control.” Insight, 27.
 Lama Zopa Rinpoche is referencing a famous verse spoken by Lord Buddha:
Buddhas neither wash sins away with water,
Nor remove beings’ sufferings with their hands,
Nor transfer their realizations to others; beings
Are freed through the teachings of the truth, the nature of things.
Quoted with commentary by the Dalai Lama in Buddhism of Tibet, 46–47.
 Regarding “directly,” the wisdom realizing emptiness initially ascertains its object indirectly—which is to say, through the medium of a generic image or “meaning generality” (don spyi, arthasāmānya). Then, through deep repeated familiarization with a strong level of concentration (utilizing the union of calm abiding and special insight), this generic image gradually dissolves until one realizes emptiness nonconceptually and directly, that is to say, with a nonconceptual wisdom (rnam par mi rtog pa’i ye shes, nirvikalpajñāna). For detail, see Hopkins, Meditation, 407–10. At the point emptiness is perceived without the mediation of a generic image, the consciousness realizing emptiness and the object emptiness appear nondualistically mixed, “like fresh water poured into fresh water” (ibid., 410). This means, explains Kensur Yeshey Tupden, that “Even the [image of its] negated object does not appear to it; no image or meaning generality [even of emptiness] appears to it either. The [emptiness or] way of being (gnas lugs) of all things that exist is all that appears to it. It is as if their aspects come toward or are cast [to the perceiving consciousness]. These are not cast by their own force (nus pa, śakti); it is [simply] their nature [to appear or] be cast in this way. Such aspects are cast toward it and the consciousness engages (’jug) with its object through the power of the object (dngos dbang). Subject and object appear as one. The subject itself is a consciousness, a conventional phenomenon. Its own aspect [as consciousness] does not appear to it. Does the person then realize emptiness? The person does, for what the consciousness realizes, the person also realizes. And such a mind has tremendous power.” See Klein, Path, 35. In terms of the bodhisattva paths, the first moment of this nonconceptual direct realization corresponds to entry to the Mahāyāna path of seeing. While on the path of seeing, this wisdom uproots the artificial conceptions of inherent existence. See Hopkins, Meditation, 96 and 177. Upon attainment of the path of meditation, this direct realization begins to uproot the innate misconception of inherent existence. Yet further familiarization with nonconceptual realization of emptiness enables the bodhisattva to proceed step by step until the most subtle obscurations are eradicated, at which point the person becomes enlightened. For a detailed account of this progression, see ibid., 91–109. For technical commentary on generic images, see Geshe Lhundup Sopa and Jeffrey Hopkins, Cutting Through Appearances (Ithaca: Snow Lion, 1989), 225–29.