मनु-उपदेशः — भूत-उत्पत्ति, इन्द्रिय-निवृत्ति, तथा पर-स्वभाव-विवेकः
Manu’s Instruction on Elemental Origination, Sense-Withdrawal, and Discrimination of the Supreme Nature
पृथग्भूतौ प्रकृत्या तौ सम्प्रयुक्तौ च सर्वदा । यथा मत्स्यो जलं॑ चैव सम्प्रयुक्तो तथैव तौ
pṛthagbhūtau prakṛtyā tau samprayuktau ca sarvadā | yathā matsyo jalaṃ caiva samprayukto tathaiva tau ||
Bhīṣma explica que, aunque ambos son distintos por su propia naturaleza, permanecen perpetuamente unidos. Así como el pez y el agua son entidades diferentes y, sin embargo, inseparables en la experiencia vivida, del mismo modo el ser (ātman) y el instrumento interior, como el intelecto (buddhi), son distintos en esencia, pero actúan conjuntamente en la existencia encarnada.
भीष्म उवाच
The verse teaches discernment: the self (ātman) and intellect/mind (buddhi) are inherently distinct, yet in embodied life they operate in constant conjunction. Recognizing this helps one act in dharma without mistaking mental functions for the true self.
In Śānti Parva, Bhīṣma is instructing Yudhiṣṭhira on philosophical and ethical foundations after the war. Here he uses the fish-and-water analogy to clarify how two different principles can remain inseparably associated in lived experience.