We must know how to function correctly in this world. If we know how to function properly, the disease won't arise. To function properly in regard to the world is to function properly towards sense impressions. In this regard the Buddha taught the initial practice of sense restraint, indriyasaṁvara: restraining the eyes, ears, nose, tongue, body and mind, so as to prevent sense impressions from overwhelming us and causing greed and hatred to arise. This means to use sati -- to know things as they are, as they arise. Whenever a sensation arises, vedanā, the feeling of pleasure, displeasure or indifference, is there. When a pleasant feeling arises, the unmindful person delights in it. When unpleasant feeling arises, the mind untrained in sati flows down the stream of proliferations to disapproval, anger, displeasure, hatred and so on.
The mind of the average person will be in this state all the time, constantly flitting from delight to aversion, and in the Tipiṭaka these two words "delight" and "aversion" crop up frequently.
Whenever we experience a sense impression there is a resulting reaction from the mind. So I say we experience life through the awareness of sensations. Thus the experience of sensation is a very important aspect of our everyday lives. If we don't practice correctly in relation to our experience of sense contact, defilements will arise, resulting in problems.
The first defilements to arise will be "delight" and "aversion." Therefore it is said to cut the stream at its beginning with sati, restraining the senses. In the beginning, we recollect whenever a sensation has arisen. Whether it is to our liking or not we should not allow that sensation to overwhelm us, leading us to proliferate under the influence of delight and aversion, and from there to further harmful thoughts. This is how to practice properly in relation to sense impressions, which is also the proper relationship toward the world. When we practice like this, the diseases won't arise.
This is one aspect of the matter, the disease which arises within through sense contact. However, if we look more deeply we see that this interaction between ourselves and the world, what we call life, is all saṅkhāra, conditioned phenomena. The world consists of saṅkhāra, which all come under the domain of the Three Characteristics: they are all impermanent, stressful and not self. The whole world is therefore just the same as our individual lives, all changing and ephemeral. It is not within our power to force it to be any other way than as conditioning factors direct it (it is anattā).
Even though the world is anattā, people still attach to it. "World" here refers to everything we come into contact with, not only our bodies but all our possessions, both living and non-living. They are all impermanent, stressful and not self, just as are our very lives. The wrong way to conduct oneself is to perceive sensations with clinging. Seeing sensations as ourselves or belonging to us, we expect them to obey our commands. When we cling to the world in this way, wanting everything, especially our possessions, to conform to our desires, to belong to us, then when those things change according to the natural laws of cause and effect, our minds manifest a state of turmoil and distress. Suffering arises. Thus, in the final analysis, the world causes disease to arise within us because it is subject to the Three Characteristics.
Summarizing, we can say that there are two distinct factors which cause the disease of suffering. First, kilesa, the unskillful interactions with the world through the influence of delight and aversion, as well as the many kinds of defilements. The second way is by the very nature of the world itself, being impermanent, stressful and not self, which causes conflict to arise in the mind of anyone who clings to it.
However, the arising of problems, regardless of whether we look on the level of our own lives, or look outward to the world in general, must ultimately stem from one and the same source. The arising of problems in the most elementary sense occurs on a moment-to-moment basis, as the mind interacts with the various sensations and becomes, as a result, spoiled, agitated and tricked by greed, hatred and delusion.
If one has mindfulness and can cut the flow of defilements, by not allowing the mind to indulge in delight and aversion, then one can maintain the mind in a clear, calm state. The disease won't arise. However, on a deeper level, one must also understand the true nature of this world and our lives in their entirety, as impermanent, stressful and not self. One can thus relax the grip of attachment. Once the grip of attachment has been relaxed, one's mind is no longer swayed or overwhelmed by the world. No matter how things go, they can no longer rule over the mind. Not following those conditions, the mind detaches itself freely from them.
This is an important point. In the end, we must be able to free our mind, to make it liberated, clear and calm at all times.
What I've been talking about here is the practice of Dhamma on various levels. Firstly, I explained the practice of Dhamma as a medicine for specific illnesses. This includes the various techniques for counteracting such defilements as macchariya, selfishness or stinginess. When this arises we would use one particular technique. If anger or envy arise we can use other techniques. On the deeper level, eventually we must know the true nature of saṅkhāras. Just by knowing the true nature of saṅkhāras we can thereby simultaneously cut defilements in all their forms, because we see that they are not worthy of holding onto. When we don't cling to things, they no longer cause us to whirl around, because we've seen their ultimate nature.