### Bhai Dooj (Yam Dwitiya): A Celebration of the Hydrological Cycle and the Continuity of Life*

The festival of Yam Dwitiya, also known as Bhai Dooj, serves as a reminder of the vital role the hydrological cycle and food chain play in sustaining life and natural balance. It educates society about the importance of maintaining the continuity, purity, and strength of these essential processes.

In the story of Yam Dwitiya, rivers are portrayed as daughters of the Sun (Surya), represented by Yamuna and Tapti. We know that the Sun's energy drives the hydrological cycle, ensuring the availability of water in rivers. This story emphasizes the interconnectedness between solar energy and the water cycle.

The story also mentions Yam, the god of death, as a son of the Sun. The Sun symbolizes both the creation and the end of life—a cycle of life, death, and rebirth that is intrinsic to the food chain and the ecological cycle.

The scientific essence of Yam Dwitiya lies in the Earth's rotation and revolution around the Sun, resulting in light and shadow on opposite sides. The side facing the Sun experiences day, while the opposite side is enveloped in night. The tale refers to the shadow (Chhaya) as a form of the Sun's wife, highlighting this scientific concept.

According to the story, Yamuna invites her brother Yam on Bhai Dooj and requests him to free mankind from the fear of death and suffering. Yam promises that those who worship the sacred Yamuna River will be relieved of their hardships. This underscores the festival’s link to the purity of rivers, conveying that clean, sacred rivers bring prosperity and good fortune while protecting against disease and the fear of death (Yamraj).

Therefore, on this scientific and ecological festival that emphasizes river conservation, we should all pledge to improve and restore the purity of our rivers. It is a day to commit to the continuity of the food chain and the reinforcement of our ecological system.

**Mythological Background:**
Surya Dev (the Sun God) and his wife Sangya Devi had two children—son Yamraj and daughter Yamuna. Sangya Devi, unable to endure the Sun's intense rays, moved away and assumed the form of Chhaya (shadow), from whom Tapti River and Shani (Saturn) were born.

In Yam’s abode, Yampuri, sinners are...