Traditional Buddhist teachings speak extensively of the six realms or paths into which sentient beings are born (gods, demigods, humans, animals, ghosts, and hell beings), and one must be careful to both present the teachings and receive them in accordance with the intentions of the Buddhas.
Are these realms actual physical environments? Yes and no. Like all other external perceptions, the six realms are internal mental representations, made to arise by the accumulated karma (impressions, experiences, beliefs, and dispositions) of sentient beings. But just because they are internal mental representations, they are not absolutely unreal. As long as we lack realization of emptiness, our perceptions are experienced as reality.
The six realms are not truly established, substantial realities, in the sense that they are impermanent and dependent on causes and conditions. And yet, they appear in great detail to those that experience them.
Dreams (nightmares, in this case) are a good analogy. While having a nightmare, we have the distinct impression that whatever is happening is actually taking place. We may even experience physical reactions: racing pulse, sweating, thrashing about, screaming, etc. Some persons have been known to die of fright during a nightmare!
Within the nightmare, the experience is very real. And yet, when we awaken, we know that nothing truly happened —it was all a bad dream. It was an internal mental representation. We may have been dreaming of being pursued by a tiger, but there is no tiger in the bedroom; it was only an internal image of a tiger in our mind. We may have dreamt of drowning, but all the time we were lying on a dry bed. We may have been dreaming of being engulfed in flames, but our skin is not scorched when we awaken.
The six realms are similar, although their duration may seem quite a bit longer. They are mental states, but while we are experiencing them, we suffer immensely. Is it not our current experience that pain seems to last much longer than pleasure? “Time flies when you’re having fun.” The opposite is also true…
Now, while some persons are ready to understand that the six realms are ‘only’ mental states, others are not. For them, these realms are quite substantial. There are persons among us (we may diagnose them as insane in today’s society) that firmly believe that what they experience in dreams or altered states of consciousness is substantially real. And for them (in terms of their subjective experience) this is a fact, regardless of what others may understand.
When the Buddhas teach about the six realms, They allow us to understand Their teachings with whatever capacity we have at the time. If we have the tendency to ascribe absolute reality to our perceptions (this common, everyday one included), we will do likewise with the six realms. If we are able to understand that this experience is an internal mental representation, then we will also be able to understand the six realms in this light.
The hell realms are the farthest distance away from our Buddha Nature, in the direction of aversion, just as the god realms are farthest in the direction of attachment. The demigod realms move us away through envy, the human realm through desire, the animal realm through stupidity, and the ghost realm through greed.
They are all mental states, distortions of clear View, and nothing more. Of course, even if they are not ‘real’ in any objective way, sentient beings experience subjective suffering in them. And yet, they are not punishments. They are merely the natural consequences of our afflicted emotions. The teachings on karma just warn us that if we do not become free of these afflicted emotions now, we are bound to continue experiencing them over and over.
The cause of these afflicted emotions is ignorance, and therefore the Buddhas do not judge anyone as evil –not even Hitler, or Stalin, or more common mass murderers. They feel intense compassion for all sentient beings, and especially for those who suffer most.
The ‘kingdom of hell’ is within us. But when we are there, it is very difficult to escape. We start blaming others for our condition, and that leads to greater fear and anger. Sociopaths are an extreme example of that. Their suffering is extreme.
The Buddhist teachings do not condone judging others, nor do they express any concept of punishment. Karma is not punitive, but corrective. When we experience suffering as a consequence of treating others poorly, eventually we come to understand that we are all in the same situation, and compassion begins to manifest, for others and for ourselves.