Dhamma, when well practiced, is like a medicine for treating the ills of life, enabling us to live our lives well. The Buddha, as the proclaimer of the Dhamma, is like a skillful doctor who prescribed particular medicines for particular illnesses. If a doctor is not skillful, even though he may have good medicine, he may prescribe it wrongly. His treatment will then not be very effective. A skillful doctor will be very effective in treating his patients, because he thoroughly understands the properties of the various medicines.
Sometimes we hear it said, "Buddhism has been with us for thousands of years, and yet we still see people fighting and in conflict. Evil still abounds. Buddhism seems incapable of dealing with it, it's useless. We may as well dispense with it." Some people see it like this.
Do you think this is true? They say that even though we've had this Buddhist religion for so many years, people are still corrupt, they still live in conflict. Religion seems powerless to stop these things. We can see no concrete results from religion at all. Better to do away with it.
To these people I say, "Well, the science of medicine has been with us for many thousands of years. Medicine is plentiful and there have been doctors curing illnesses throughout the ages, for thousands, even tens of thousands, of years. And yet we see disease and illness still abound. If what you say is true then we must also say that the science of medicine is redundant, we may as well throw that out, too."
This leads us to consider that this body of ours is by nature a breeding ground for illness, and is subject to pain and aging. We have to procure medicines and exercise the body in order to maintain our strength and live as free of illness and pain as we can.
Therefore the science of medicine, and the profession of doctor, are still very valuable things. As long as there are people in the world there will be pain and disease, so there must also be treatment for them.
Similarly, in regard to religion, as long as there are people in the world there is also "mind". Like the body, the mind can be weakened and damaged. Problems arise in the mind and cause discontent. The quality that disturbs the mind is what we call in Buddhism dukkha (suffering). As long as there are people living in this world there will be suffering, so we must also have a treatment for it. When one person is cured there are still countless others to follow.
Thus religion can be compared to the science of medicine, and the Buddha to a great doctor. Having cured many people in his own time, he also left us his teaching so that we who follow after him can treat our own illnesses.
In our lives we have both body and mind. As for the body, the doctors usually deal with its illnesses. It is the Dhamma, however, that we must use for dealing with our lives as a whole, particularly the mind.
What is the disease that incessantly hounds the mind? It is the disease of defilements (kilesa). Whenever greed, hatred or delusion arise within the mind they cause discontent and suffering to arise. Such a mind can be called an ill or diseased mind. When diseases such as greed arise, they stifle and oppress the mind, causing it to become obsessed with some object or other. The mind is not spacious or clear. When hatred arises, it heats and agitates the mind. This is another disease that unsettles the mind, as do all other kinds of defilements.
The healthy mind should have the qualities of lightness, radiance, clarity and calm. Whenever defilements arise, these qualities disappear. Clarity becomes murkiness, calm changes to excitement and agitation, the quality of lightness gives way to oppression and conflict. These are the symptoms of the diseases of the mind, which are all caused by defilements. So we say that defilements are a disease which must be treated.
In this regard the Buddha's teaching is like a handbook of medicines. Some of the medicines are for specific illnesses. The cultivation of goodwill, for example, is for treating the disease of anger. Apart from goodwill, which acts like a refreshing, cool shower on the mind when it is oppressed and disturbed, there is also patient endurance to aid in driving annoyance and irritation from the mind, or karunā, compassion, for counteracting destructive thoughts, or paññā, wisdom, for brightening the mind and making it clear and light.
There are many different types of Dhamma medicine, and they must be used appropriately. One who aspires to skillfulness in using these medicines should follow the example of the Buddha, whom we revere as the greatest "Dhamma Doctor," in that he prescribed medicines with the greatest proficiency. If a teacher is unable to use these medicines skillfully, his teaching may become so much hot air. Anybody listening to it would have to rely on his own wisdom to choose the teachings appropriate to his needs, and if he wasn't skillful he might not obtain much benefit from the teaching.