There are two concepts fundamental to the Buddhist view on the nature of reality, or the world as we experience it. The first is that all things have no inherent existence. They are Empty; they have no eternal nature. Secondly, that things appear to be what they are because of our own conditioning.
To explain this second principle, Vasubandha (Asanga's brother, 3rd century CE) used the example of the wardens of Hell. If the demons, who see to the appropriate torture of those whose karma has led them there, take rebirth in the hells because of their karma, then wouldn't they also experience the suffering? How could they oversee their work if they were subject to the torments of the hells, along with their charges or "victims?"
Vasubandhu says that the wardens of the hells merely proceed from the minds of the ones who are there suffering in torment. They are projections, just like many other features of existence. Hell is a kind of hallucination.
Hell R Us
In the Buddhist world, between the 4th and 5th century there appeared The Sutra of the Remembrance of the True Law which presents the subject of the hells as a journey into the self.
In the Chinese Buddhist community where The Sutra of the Remembrance is well-known, it is no laughing matter to say things like, "Mother, you could die tomorrow without having . . . ." Such remarks can be taken to allude to matricide.
The hells (Jap. Jigoku) are viewed as a creation of the mind, filled with self-deception and egocentrism. The first 4 in the descriptions that follow are consequences of physical actions, the 5th is the result of crimes of speech and the last 3, the result of mental faults or imperfections -- stains, really -- called the kleshas.
The first hell is the realm of murderers. Here suffer those who kill for pleasure or desire. It is the Hell of Repetition where those who kill for pleasure or to fulfill some desire end up. These murders brag about their actions, having no appreciation of the value of life. This is not the destination of those who kill as a consequence of some other goal.
The next destination is known as Black Rope Hell. Here we find those who have killed during the commission of some other crime. The point is made that, though people may commit crimes as members of a group, they must suffer the consequences as individuals.
Great black birds chase the wrong-doers and pluck out their eyes; demons pull out their tongues and entrails. They are forced to drink molten copper, and suffer multiple stabbings.
Certain types of killing, or stealing along with sexual indulgence, lead to the Crowded Hell. Having improper attitudes to physical love leads to Fire-jar Hell where self-proclaimed monks, or those who misuse their office are tormented with fire at the organ that caused the wrongful behaviour. For example, those who cling to the vision of a desirable woman will have their eyes burnt. Their ears will burn if their wrong-doing is a result of their attachment to a woman's voice or her laughter.
Screaming Hell is the destination for those who misuse intoxicants. This is the destination for those who seduce people using alcohol or other drugs, who trap animals in a similar way or cause people to be under their power through the selling of drugs.
The Great Screaming Hell is the place for those whose misdeeds are via sound or the voice, generally. Those who use language to confuse or to sow discord will find themselves here. Here the body may be infested with vipers that need to chew their way out; with each lie, another nest of snakes is created.
Those who hold false views can experience the Hell of Burning Heat. They who deny that a law of cause and effect [karma] is in operation and hence, by extension, deny the existence of good and evil can know the Diamond-beak Hornet Hell. There, hornets sting so that blood spurts out which the sinner must then drink. This induces great hunger but the victim has only his own flesh on which to feed.
The seventh Hell is related to the sexual defilement of religion. It is called Burning Hell of String-like Worms. Those who seduce nuns or monks are tied up and pegged to the ground where a demons stuffs worms up their anus which travel up through the alimentary canal eating everything in their way until they crack their way out of the head of the sinner.
The last of the 8 hells is the Hell of No Interval. This is the destination of those committing the 5 most serious crimes: 1. pre-meditated murder of one's mother 2. pre-meditated murder of one's father 3. pre-meditated evil intent to harm an Enlightened One and to rejoice in that action 4. pre-meditated intent to harm the Buddhist community or sangha 5. pre-meditated murder of arhats or bodhisattvas.
The view among many teachers is that these descriptions of the hells remind Buddhists of their aspirations, the precepts they have taken, and of the imperfections that are common to human nature. The hells serve as metaphoric mirrors.
The hells may number 8 as above, or 10 or even 136 depending on the tradition. Tibetans generally consider that there are 18 "Kingdoms of the Demons," and 2 types of Hell -- the hot and the cold.
Here are some other well-known references:
Lotus Sutra 3:
"After their lifetime's end they will enter the Avici [un-spaced, no interval] hell for a complete kalpa. Reborn at each kalpa's end, they thus go on revolving unto innumerable kalpas.
When they come out of hell, they will degrade into animals such as dogs or jackals with lean-cheeked forms, blue-black with scabs and sores, the sport of men. Moreover by men hated and scorned, ever suffering hunger and thirst, bones and flesh withered up. Alive, beaten with thorns; dead, with shards and stones.
By cutting themselves off from the Buddha seed, they receive such recompense."
"Then the man of unwholesome deeds boils in water infested with worms. He cannot stay still--the boiling pots, round and smooth like bowls, have no surfaces which he can get hold of. Then he is in the jungle of sword blades, limbs mangled and hacked, the tongue hauled by hooks, the body beaten and slashed.
Then he is in Vetarani, a watery state difficult to get through, with its two streams that cut like razors. The poor beings fall into it, living out their unwholesome deeds of the past. Gnawed by hungry jackals, ravens and black dogs, and speckled vultures and crows, the sufferers groan. Such a state is experienced by the man of unwholesome deeds. It is a state of absolute suffering. So a sensible person in this world is as energetic and mindful as he can be."
The Mahayana aspiration is to help all beings everywhere, therefore certain heroic bodhisattvas may determine to go to Hell to help the suffering beings there. Kshitagarbha who is generally depicted standing with his jangling staff, is one of those.
The Kshitagarbha Sutra has that bodhisattva explaining to Queen Maha-Maya who is Buddha Shakyamuni's own mother:
Then, there are the yakshas (demons) with eyes like electric bulbs and hands in the shape of steel claws to scratch the sinners. These yaksas pierce the sinners' bodies, throw them into the air and the fall kills them.
There are also iron eagles which hook the eyes of sinners, and iron snakes which curl round sinners’ necks. Long nails pierce the sinners’ limbs, their tongues are pulled out by iron tongs, and their intestines are sawn up. Molten metal is poured into their mouths. Hot iron wires are used to bind their bodies.
Sinners suffer according to their evil actions by encountering
innumerable births and deaths for kalpas and kalpas without any hope of escape.
When this world comes to an end, sinners will be transferred to another world,
and in the new world they endure more punishment.
In the Surangama Sutra, the Buddha explains how karma determines rebirth, so that
From Tenzin Sherab, a Gelugpa monk:
But Hell Does Not Exist
Khenpo Karthar, abbot of Karma Triyana Dharmachakra, has said that "From the Buddhist perspective, such a thing as a hell does not exist in absolute reality." Nevertheless, he continues, alluding to the law of karma, "As long as we have serious patterns of aggression, no matter how strongly we might like to believe there is not such a realm or psychological state, we will still experience it because we have the cause for the consequences."
Khenpo Karthar goes on to say that it is similar to beings in other realms trying to understand the human one. It is difficult to accept because their existence [their kind of suffering] seems real to them, and ours does not.
At least in the human realm we have the possibility of seeing the nature of illusion; for those in the hells, experience is " ... so continuous, so intense and claustrophobic, that it does not even give them a break where they could think, 'Maybe this could be different.' "
And, a transcript of a teaching by Khenchen Konchog Gyaltsen (Drikung Kagyu):