Mundaka 1.1.3 Trans & Comms

śaunako ha vai mahāśālaḥ aṅgirasaṁ vidhivad upasannaḥ papraccha. kasminnu bhagavo vijñāte sarvamidaṁ vijñātaṁ bhavatīti. (1.1.3) 

śaunakaḥ – Śaunaka; ha vai – indeed; mahāśālaḥ – the famous householder; aṅgirasam – to Aṅgiras; vidhivat – as per the stipulations; upasannaḥ – approached; papraccha – (and) asked; iti – thus; bhagavaḥ – O Revered Sir!; kasmin nu vijñāte – by knowing which one thing alone; idam – this; sarvam – all; vijñātam – known; bhavati – becomes 

Śaunaka, the famous householder, approached Aṅgiras as per the stipulations and asked thus: ‘O Revered Sir! By knowing which one thing alone, does everything become known?

~Dayananda

The great householder Śaunaka duly approaching Aṅgirā in the prescribed manner asked, “What is That, my Lord, having known which all these become known”?

Śaunaka wants to know what is that Knowledge which is the very substance of all knowledges. In short, he wants to know the light principle in our intelligence by which knowledge of things are illumined for us during our existence.

~Chinmayananda

Saunaka, the great householder, approached Angiras in the proper manner and said: Revered sir, what is that by the knowing of which all this becomes known? 

According to Non-dualistic Vedanta an effect has no real existence apart from its cause. Therefore when a man knows the cause, he also should know that the effect has no reality independent of it. Brahman is the ultimate cause of the universe. When one knows Brahman, one also knows that the universe has no reality independent of Brahman. 

~Nikhilananda