The Sanlun school, also known as the Three Treatise school, is a Chinese Madhyamaka school that emerged during the sixth century. This school is based on the teachings of Nagarjuna, an Indian philosopher who is considered the founder of the Madhyamaka tradition. The Sanlun school places great emphasis on the concepts of emptiness and dependent origination, and their relationship is a central aspect of their philosophy.

The Sanlun school views emptiness and dependent origination as two sides of the same coin. Emptiness, or shunyata, is the ultimate reality according to this school. It is the understanding that all phenomena lack inherent existence and are empty of any inherent self-nature. This emptiness is not a negative or nihilistic concept, but rather a liberating one. It means that all things are interdependent and have no fixed or permanent nature.

Dependent origination, or pratityasamutpada, is the understanding that all phenomena arise in dependence on causes and conditions. This concept is closely related to emptiness, as it highlights the interdependent nature of all things. According to the Sanlun school, emptiness and dependent origination are mutually dependent and cannot be separated. Emptiness is the ultimate truth of all phenomena, while dependent origination is the conventional truth that explains how things appear and function in the world.

The Sanlun school also teaches the concept of the two truths, which further explains the relationship between emptiness and dependent origination. The ultimate truth, or paramarthasatya, is the understanding of emptiness, while the conventional truth, or samvritisatya, is the understanding of dependent origination. These two truths are not contradictory but complementary. Emptiness is the ultimate reality, while dependent origination is the conventional reality that we experience in our daily lives.

In the Sanlun school, the relationship between emptiness and dependent origination is often described using the analogy of a dream. Just as a dream is empty of inherent existence but appears to have a conventional reality, all phenomena are empty of inherent existence but appear to exist in our conventional reality. This analogy helps to illustrate the interdependent and complementary nature of emptiness and dependent origination.

In conclusion, the Sanlun school views emptiness and dependent origination as two sides of the same coin. Emptiness is the ultimate reality, while dependent origination is the conventional reality that we experience. These two concepts are not contradictory but complementary, and understanding their relationship is crucial for attaining enlightenment and realizing the true nature of reality.