It's actually part of a larger sentence: "Tat tvam asi, iti Pushan apavrinu".
Here's a breakdown of the meaning:
* Tat tvam asi: This is the most famous part of the phrase, translating to "That thou art". It's a statement of the fundamental unity of all existence, implying that the individual self (atman) is ultimately the same as the universal Self (Brahman).
* Iti: This means "thus" or "so."
* Pushan: This is a Vedic deity associated with sunlight, nourishment, and prosperity. He is often invoked as a protector and guide.
* Apavrinu: This means "reveal" or "uncover."
Putting it all together:
"Thus, O Pushan, reveal to us that thou art."
Interpretation:
The phrase suggests that the knowledge of "Tat tvam asi" is a hidden truth that needs to be revealed by a guide or teacher. Pushan, as a source of light and knowledge, is being asked to reveal this profound understanding of the oneness of all existence.
Significance:
This statement is a cornerstone of Advaita Vedanta, a school of Hindu philosophy that emphasizes the non-dualistic nature of reality. It's a powerful declaration of self-realization, urging individuals to recognize their true nature as being identical to the ultimate reality.