“The attitude which one engenders when one speaks of Bodhicitta is an attitude which refers to all sentient beings; the essence of the consideration of all beings is compassion. This must be developed in a certain sequence. We must begin by understanding the real situation of all beings. Then, meditating on it, you will develop the attitude and you will get used to it and train yourself.

The situation that must be understood is that wherever there is space, it is filled with sentient beings. There are so many sentient beings that one can say they are numberless. Each sentient being has been one of one's parents so many times that the number of times that any given sentient being has been one of one's parents is a number beyond reckoning, as the Buddha said. Also, there is not any single being that has not been one's parent. At the time when beings were one's parent, they showed the same kindness toward one as one's parents in this life. This means that, for example, if one had been a human being in a lifetime, one's mother in that life would have carried one in her womb, continually worrying about one's fate, whether one would be born alive whether one would be healthy, and undergoing incredible suffering and sacrifice in order to keep one alive. After one had been born, one's parents would have looked after one and sacrificed everything for one's benefit and welfare. Every sentient being has done this for each of us countless times.

An example of how rebirths can occur comes from the time of the Buddha when a disciple of the Buddha, an Arhat named Katayana, went begging one day and met a woman sitting by the side of the road with a small child on her lap whom she was caressing very affectionately. The woman was eating fish and sharing it with the child. A large dog was trying to get the bones out of the fish. She scolded the dog, pushing it away and trying to avoid giving it fish. With his extraordinary cognition, Katayana examined the past lives of these beings. He saw that the fish had been the woman's father in her previous life, the dog she was beating had been her mother, and the child she was cuddling on her lap had been her worst enemy, someone who had constantly insulted and scandalised her in public, and someone she had also fought violently.

All sentient beings, who have been one's parents countless times, and countless times been as kind to one as our parents in this life, are going through an unending and intolerable experience of suffering through wandering round and round in the six realms of samsara. This is actually an ocean of suffering because what is being experienced is, in any form of birth, only suffering. As denizens of the hells, beings experience the agonies of heat and cold; as hungry ghosts, the agonies of hunger and thirst; as animals, the suffering of killing and being killed for food and survival; as humans, the four great sufferings of birth, aging, sickness, and death (and beyond those sufferings, the eight or sixteen lesser sufferings as well); as asuras, the sufferings of jealousy and constant fighting; as gods, the sufferings of death and falling to a lower rebirth.

If one actually understands the fact that these beings who have been so kind to one are undergoing an endless experience of intolerable suffering, then one will give rise to the attitude, "What can I do, what can be done to establish all these beings in happiness and freedom from suffering?" This is the beginning of loving-kindness and compassion. This is the reason why we recite, "May all sentient beings have happiness and the causes of happiness; may all sentient beings be free from suffering and the causes of suffering. " The cause of happiness is the practice of virtuous action, and the cause of suffering is the practice of non-virtuous action. So the attitude that is automatically, necessarily given rise to at this point, is the aspiration that all sentient beings, right now, experience happiness and be free from suffering, and also that they accumulate the causes of their future happiness and be free from the accumulation or causes of their future suffering. This is the development of loving kindness and compassion.

Since the essence of the mind is emptiness, there is nothing in the mind that can die or be destroyed, which means that we have always had this mind and, until we attain Buddhahood, we will continue to be reborn and undergo the sufferings of samsara. This can be illustrated by an example. The mind is empty in the sense that space is empty, and it is impossible to kill or destroy space.

This can further be illustrated by examining the situation of mind in the various stages of life. When we are born, or more specifically, conceived, the parents do not see a mind come floating into the womb. There is no material form to the mind of the being that enters the womb. There is nothing to be seen. When someone dies, one does not see a mind come floating out of the body. There is no materiality or form or physical existence to the mind as such that can be perceived. Even during our lifetime we can't find, pinpoint, or describe the mind with reference to any kind of material, physical, or real characteristics. Thus, it can be established that the mind is emptiness. In both the Hinayana and the Mahayana, it is accepted that direct realization of the emptiness of the mind is the realization of the egolessness of the individual. 

Although the mind of every sentient being is empty in this way, every sentient being conceives of this empty mind as an I, as an ego. At the same time, because of the radiance or projection of the mind, which is inseparable from the empty aspect of the mind, there are the confused appearances that we experience. For example, as human beings, we experience the confused appearance or hallucinations that are characteristic of the human life. The nature of these is like a magical illusion, like a dream, like the reflection of the moon on water, like a rainbow, and so forth. We could say that it's very much like film or television. In the case of television, there is a small box. The images that we see do not exist as such any where, and certainly aren't what they appear to be. It's hard to say where they are coming from, but they certainly do arise in this small box. That is very much like the nature of hallucinations or confused appearances of samsaric existence. The illusory nature of what we experience can be seen most clearly by examining the dream state. One can see very clearly by examining the process of dreams that everything we experience is actually nothing other than the mind. Because what happens when we go to sleep is that our minds become dull and stupid and as a result, we experience a variety of hallucinations. At the time, these appear to be of the same nature or quality as what we experience when we are awake, except that when we wake up, we can't find them anymore. They have disappeared. For example, when we are dreaming, we might see places, people, objects, and events, but when we wake up they are not around us. They are not even inside our body; they are nowhere. They were simply projections of the mind. Everything we experience is like that."

Teaching by Very Venerable Kyabje Kalu Rinpoche