Three characteristics of existence (Anicca, Dukha and Anatta)

The three characteristics of existence of the phenomenal world (The three signata) are Anicca (Impermanence), Dukha (suffering/unsatisfactoriness) and Anatta (Non-self). The realisation of these three fundamental truths can lead to true insight and enlightenment.

Anicca 

Anicca (Impermanence) means that nothing can be a permanent everlasting entity as everything that arise will cease.

In Mahaparinibbana sutta:
“Impermanent are all component things,
They arise and cease, that is their nature, 
They come into being and pass away.
Release from them is bliss supreme.”

If we look at ourselves, we will find that our bodies and feelings are impermanent. They are subject to constant changes: we will age, diseased and finally die. Similarly, our mental feelings are impermanent. We cannot be in the happy or sad states forever, everything will pass. Everything around us including natural phenomena like the solar system and eco system are changing all the time, we can't predict earthquakes, droughts and typhoons. Not one thing will last forever.

This process of constant changes go on constantly even without our noticing it. Our relationships are also subject to the characteristic of impermanence and changes. Friends can become enemies, enemies can become friends. Our possessions like clothes, wallets, furnitures are also impermanent, they wear and tear with time and we get new ones when the old ones get worn out. All of them will decay and eventually be destroyed.

Understanding impermanence is important so that we don't lock ourselves into fixed, artificial unchanging ideas of our relationships with others. Similarly, in one’s career and normal life, we can't succeed if one does not keep abreast of changing situations and does not work hard to keep up with the changes. So whether it is in regard to our personal life or in regard to our public life, understanding impermanence is necessary if we are to be effective and creative in the way that we handle our personal or professional affairs.

The understanding of impermanence (anicca) is an antidote to desire and ill-will. It is a key to understanding the nature of things, to see the reality of things. when we understand anicca (impermanence), we also begin to see that things have no substantial existence of their own (non-self). So in this sense, impermanence is directly related to the third of the three characteristics, the characteristic of not-self. 

Dukha (suffering)

Dukkha (suffering/unsatisfactoriness) is the second fundamental characteristic of existence and the First Noble Truth of the list of Four Noble Truths.

It has been classified further into three aspects for better understanding:
I. Intrinsic suffering (dukkha-dukkha)
II. Suffering in change (viparinàma-dukkha)
III. Suffering due to formation (sankhàra-dukkha)

Physical and mental painful feeling are called intrinsic suffering. They arise because of changes in our body (we feel pain and fall sick) and also changes to our feelings (mental suffering). In this way intrinsic suffering is called direct suffering.

Physiological suffering: Suffering of birth, old age, disease and death illustrated in first noble truth explained the physiological aspect of the issue.

Psychological (Mental) suffering: Association of what is not dear, separation from what is dear and not getting what one wants also cause psychological suffering.

The doctrinal aspect of suffering is stated in brief in the discourse referring to the clinging or grasping of five aggregates namely:
i. grasping of materiality (råpa upàdàna)
ii. grasping of feeling (vedanà upàdàna)
iii. grasping of perception (sa¤¤à upàdàna)
iv. grasping of mental formation (sankhàra upàdàna)
v. grasping of consciousness (vi¤¤àna upàdàna)

Buddha once asked Venerable Sariputta on real nature of feelings. Venerable Sariputta replied “Threefold indeed are those feelings and sensations: Pleasant, unpleasant and neither pleasant nor unpleasant but all these three feelings are impermanent, transient. When one realizes that whatever is transient must give rise to dukkha (suffering), no desire after them arises.”

The Buddha has said that whatever is impermanent is suffering, and whatever is impermanent and suffering is also not-self. Whatever is impermanent is suffering because impermanence is an occasion for suffering. It is an occasion for suffering and not a cause of suffering because impermanence is only an occasion for suffering so long as ignorance, craving and clinging are present.

Because our ignorance of the reality of things, we crave and cling to objects in the hope that they may be permanent, that they may yield permanent happiness. When we lose things that we long to be permanent, impermanence becomes an occasion for suffering. The way out of suffering as per fourth noble truth is the eightfold path to absolute happiness of Nibbana.

Anatta (Non-self/ Egolessness)

The theory of egolessness / non-self (anatta) is the third of the Three Characteristics of Existence taught in early Buddhism. In pali “Atta” means Ego. Those who believe in an eternal being and unchangeable ego were called eternalists and those who rejected the theory on empirical grounds were called nihilists.

The rejection of the idea of "I" stands for the rejection of it’s substantiality, permanence and changeless reality. Buddha rejected external soul or being.
“This is not mine. This is not my self. This is not what I am.”

In the second discourse “Anattalakkhana Sutta” Buddha mentioned that if the 5 aggregates mainly the body, feeling, perception, mental processes and consciousness were self then all of this will be permanent. But all these were impermanent (Anicca), everything is beyond our control hence anatta (non-self).

The Buddha has said that the self cannot be found in the body or the mind. The body is not the self. For if the body were the self, the self would be impermanent, then we would not be subjected to change, decay, destruction, and death. The self is not in the body. If we search our body from the top of our head to our toes, we cannot locate the self.

Similarly, the mind is not the self  and is subject to constant change. The mind is forever jumping about like a monkey. The mind is elated at one times and depressed at other times. The self does not possess the mind because the mind becomes excited or depressed against our wishes and we can't willed our feelings. The self is not in the mind. 

When we understand non-self (Anatta), we can give up this belief in an independent and permanent self and understand anicca (impermanence). 
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Even more importantly, understanding not-self is a key to enlightenment. The belief in a self is associated with ignorance, and ignorance is the most basic of the three defilements. When we have this conception of self, we respond to the persons and things around us either with desire or with aversion. When we understand holding onto the self is the source and the cause of all suffering, and when we understand that the rejection of the self is theend of suffering, then we will let go of defending, protecting and preserving the self.

When we understand that all things are impermanent (anicca), are full of suffering (Dukha), and are not-self (anatta), then our understanding of the truths is not merely intellectual or academic but through study, consideration and meditation, the facts of impermanence, suffering and not-self become part of our immediate experience. Through the understanding of impermanence, suffering, and not-self, we will have freed ourselves of the fundamental errors that imprison us within the cycle of birth and death (samsara). We can then correct the error of seeing things as permanent, the error of seeing things as pleasant and the error of seeing things as self. When these delusions are removed, wisdom arises. And when wisdom arises, one experiences the peace and freedom of Nibbana.

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