Heat, for example, is a fact. Heat is not characteristic of water, as water is not always hot. The heat of water depends upon other factors like sun or an electric stove. But heat is a characteristic of fire because fire is always hot and heat of fire does not depend on any other factors. Heat is always connected with fire and tells us something about the nature of fire.
When the Buddha taught that there are three characteristics of facts of existence. They are generally found in all that exists and so they can tell us something about the nature of existence.
The three characteristics of existence taught by the Buddha are Impermanence, Suffering and Impersonality.
The Buddha taught that all existence is impermanent because there is nothing internal or external whatsoever which is permanent, stable, lasting, not subject to decay and destruction, and forever the same. Everything changes continuously. Existence is like the flowing water of a river or the burning flame of a candle, which is never the same in two consecutive moments.
Our body, for instance, is made up of material elements such as flesh, bones and blood, which are impermanent. From the moment of our birth, the body constantly undergoes change. The human mind, too, is dependent on many factors. It is in constant change. It is like a monkeys forever jumping about, never still for even a moment. Thus neither the body nor the mind is permanent and unchanging.
Science teach that apparently permanent objects like the oceans, continents, mountain ranges and even the earth, the sun and the solar system are constantly changing and will some day become extinct. When all these are also subject to change and destruction, one cannot doubt the impermanence of life. Life can end at any moment. No one can avoid death and the destruction of the body.
Understanding the characteristic of impermanence benefits people in two important ways. Firstly, it can improve human relationships and activities. Secondly, it can encourage people to follow the Noble Eightfold Path.
Often people find that they make mistakes in their relationships with other because they fail to take into account the changes that constantly occur in themselves and others. Often friendships die because one or both parties fail to realise that their friend’s personality, interests and attitudes have changed.
When one realises that people and situation are impermanent and constantly changing,, one will approach each moment of a relationship with an open mind. One will be able to react to each new situation without clinging to outdated ideas about people. Relationships can then develop fruitfully. Success in life depends on one’s ability to adapt to change in situations and to make the most of new opportunities arising.
Having understood that youth, health, material well-being and even life itself are impermanent, people should then make the most of those favourable circumstance while they last. This means that they need to practice the Noble Eightfold Path in order to achieve happiness and Enlightenment. The Buddha’s last words were: "Subject to change are all things, Strive on with diligence".
The Truth of suffering is the first of the Four Noble Truths taught by the Buddha. Suffering is a fact of life which people can see for themselves. It is one of the three characteristics of existence.
Whatever is impermanent is also suffering. Everything which arises will last only for a time, then it decay and finally dies. Repeated birth and death is hard to endure, It disturbs one’s peace and mind and is a cause of suffering.
Thus old age, sickness and death which are evidence of the impermanence of life are forms of suffering. Since people tend to cling to youth, heath, relationship and material achievements, the realisation that these are impermanent, cause anxiety and fears. It is said that even the gods trembled when the Buddha reminded them that the heavens are also impermanent.
Understanding that suffering is universal and inevitable enables one to face the realities of life with calmness of mind. One will be able to cope with old age, sickness and death without becoming disheartened or desperate. It also encourages people to look for solution to the problem of suffering just as Prince Siddhartha did.
People often think that there must be a personality or self that is real and permanent, otherwise they would not exist or experience things in life. However, the Buddha taught that there is no real, permanent and independent personality or self at all. This is the third characteristic of existence.
If a permanent and independent self really existed, one should be able to identify it. Some people may say that the body is the self, or that mind is the self. However, both ideas are wrong. Both body and mind are impermanent, ever changing and subject to destruction. They depend on many factors for their existence. Neither body nor mind can possibly be the permanent and independent self.
If the body were the self, it would be able to will itself to be strong or fair. However the body grows tired, hungry and falls sick against its will, so the body cannot be the personality or self.
Similarly, if the mind were the self, it would do whatever it wished. But the mind often runs away from what it knows to be right, and run after what is wrong. It becomes disturbed, distracted and excited against its will. Therefore the mind is also not the self.
When people say, for instance, "I am going to work", they are just using a convenient name I for a collection of physical and mental factors. In reality, there is no I or self.
So long as people think that the self is permanent and independent, they are bound to be self centred and egoistic. Not only will feel constantly threatened by people and situations, but they will also feel compelled to protect themselves, their possessions, and even their opinions, at any cost.
But once people realise that the self is just a convenient name for a collection of constantly changing physical and mental factors, they will no longer cling to it in fear and insecurity. They will find it easier to grow, learn, develop, and to be generous, kind and compassionate because they will no longer need to be constantly on the defensive.
Understanding the fact of impersonality can help people deal more effectively with everyday situation. It encourages the cultivation of Good Conduct and helps one to progress towards happiness, peace and Enlightenment.
Impermanence, Suffering and Impersonality are the three characteristic of existence. Whatever is impermanent is suffering, and whatever is impermanent and suffering is also without an independent self. Those who realise the truth of these three facts of existence will be able to overcome suffering because their minds are freed from delusions of permanence, pleasure and the self.