The Sanlun school, also known as the Three Treatise school, is a Chinese Madhyamaka school that emerged during the 6th and 7th centuries. This school is based on the teachings of Nagarjuna, an Indian philosopher who is considered the founder of the Madhyamaka school.

According to the Sanlun school, there are three fundamental principles, known as the three marks of existence, that are present in all phenomena. These three marks are impermanence (anitya), suffering (duhkha), and non-self (anatman). Let's take a closer look at each of these principles.

The first mark of existence, impermanence, refers to the idea that all things are constantly changing and are in a state of flux. This includes both physical objects and mental states. Nothing in this world is permanent, and everything is subject to change. For example, a flower may bloom and wither, a person may age and eventually die, and even our thoughts and emotions are constantly changing. The Sanlun school sees impermanence as a fundamental characteristic of existence and teaches that attachment to impermanent things leads to suffering.

The second mark of existence, suffering, refers to the unsatisfactory nature of existence. The Sanlun school believes that all beings experience suffering in one form or another, whether it be physical, emotional, or psychological. This suffering is a result of our attachment to impermanent things and our constant desire for things to be different than they are. The Sanlun school teaches that by understanding the true nature of suffering, we can overcome it and achieve liberation.

The third mark of existence, non-self, refers to the idea that there is no permanent, unchanging self or soul. The Sanlun school teaches that the concept of a self is an illusion created by our attachment to impermanent things. In reality, all things are interconnected and interdependent, and there is no separate, permanent self. This understanding of non-self is crucial in breaking free from the cycle of suffering and achieving enlightenment.

In conclusion, the three marks of existence according to the Sanlun school are impermanence, suffering, and non-self. These principles help us understand the true nature of existence and guide us towards liberation from suffering. By recognizing and accepting these three marks, we can cultivate a deeper understanding of the world and ourselves, leading to a more peaceful and fulfilling life.