Who is Virat Purusha?
The concepts are similar. In his introduction to Brahma Sutras 3.3, Sankara says (Swami Vireswarananda translator):
It is not possible for the ordinary man to grasp the Infinite. Therefore the scriptures present various symbols of Brahman, such as Prana, Akasa, and mind, for the beginner to meditate upon. Sometimes they prescribe the cosmic form of Brahman (Vaisvanara) for meditation. These different methods of approaching the infinite Brahman are known as Vidyas or Upasanas.
Further in verse 4.1.5:
(The symbol is) to be viewed as Brahman (and not in the reverse way), on account of the elevation (of the symbol thereby).
Virat is to be viewed as Brahman, Brahman is not to be conceived as Virat. These are means for us to comprehend Brahman. We cannot meditate or conceive of Nirguna Brahman, we can only contemplate Saguna Brahman (Virat). The sky as His head, etc., are means for us to conceive That which is unconceivable. Avângmanasogocharam, meaning that which is incapable of being grasped by word or mind.
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