Literature Reference: 二室遥相望，云回洞里天。——《送赵法师还蜀因名山奠简》 The two peaks gaze at each other from afar, clouds circle the heavenly cave. Source from 'Song Zhao Fashi Huan Shu Yin Mingshan Dian Jian'.
洞:
天: The sky, encompassing all things between heaven and earth, when used in a name, often symbolizes grand ambitions and aspirations, as well as a lifetime of unwavering integrity. This character represents the auspiciousness of pure yang and solitary excellence, capable of bestowing the profound utility of great endeavors and significant achievements.
Meaning: Dongtian refers to a celestial realm or a deep cave, symbolizing mystery and transcendence.