A simple form of the Buddha’s teaching is found in the Four Noble Truths. The first of these is the doctrine of dukkha: there is suffering. The Three Marks of Existence provide a deeper understanding of what is meant by dukkha. These three characteristics of existence are accepted by all schools of Buddhism.
The first mark is anicca, or Impermanence. All things in reality change and that change is constant. There is no permanent state because all things are dependent on other constantly changing things. This is also known as conditioned existence because all things are conditioned by what they are dependent upon. Even our mental states are constantly changing from one moment to the next. It is important to accept this concept so we can adjust to the reality of life and ease the anxiousness we feel in response to changing circumstances.
The second mark is anatta, or Insubstantiality. A person is not a distinct identity that is fixed. Each person exists as a process of changing aspects of being that are called skandhas. When these skandhas are put together they give the sense of an individual. However, this individual is insubstantial because the skandhas are impermanent, interdependent and constantly changing. The five skandhas are rupa, the physical material of the universe; vendana, sensations that come from interaction with the rupa; sanna, the perception of matter and thought through sensations; sankhara, deliberate mental formation of a response to that perception; and vinnana, the state of mind resulting from a pattern of mental formations, or consciousness. Each skandha is dependent on the other, and none can exist if even one is removed. This changing process we identify as a person can continue in rebirth, as a plant continues the process of the plant from which it originates.
The third mark of existence is dukkha, or Suffering. This mark can be understood in three ways. Suffering itself is understood in our direct experience of pain or uneasiness, but this is not our entire experience of life in general. We also experience dukkha in frustration when pleasant experiences end, and we long for more. The third means of understanding dukkha is the experience of not being completely satisfied when expectations are unfulfilled. This results in dissatisfaction or a feeling that life is meaningless.
Recognizing the three marks as a reality of existence, rather than as abstract concepts, is a sign of wisdom within Buddhism.