Achintya is that which is beyond imagination or intellection. Acintya is that which does not come within the grasp of prakriti or primordial matter. According to Upanishads, atman or Brahman is Achintya. The Vedic seers realized the supreme through their intuitive power. Being a fact only of experience, words are inadequate to give expression to Brahman. Atman was beyond definition. Yajnavalkya could only describe it in negative terms – neti, neti. It is not in space or time; it is free from causal necessity. It is above all conceptions and conceptual differentiations. It is inconceivable or Achintya. Yet, it is not to be confused with non-being.
Atman is immutable. He is sat, nitya (eternal) and mahat (greater than the greatest). The concept of the Infinite is Achintya. And that alone is the highest bliss.
He is Achintya because he is all pervading. He is called Vishnu, which means all pervading. Hence, he is called bhuh, bhuvah, svah (the earth or intermediate field and heaven). The entire universe is his form.
Jiva or the individual self is Chintya (conceivable). However, true self knowledge means realization of the oneness with the Supreme Self. At that stage of knowledge, the jiva becomes inconceivable or Achintya. The concept of emancipation or moksha means self realization on the part of an individual – the realization that atman and Brahman, the self and the self are one and the same.
Achintya is one of the thousand names of God Vishnu mentioned in the Vishnu Sahasranama. Being formless, the Supreme Self is not determinable by any kind of knowledge. He is himself the witnessing, self-certifying knowledge.
Source -
The Hindu Mind (1998) - Bansi Pandit - Glen Ellyn, II B and V Enterprises
Encyclopedia of Hinduism Volume I page 34 - IHRF
Source -
The Hindu Mind (1998) - Bansi Pandit - Glen Ellyn, II B and V Enterprises
Encyclopedia of Hinduism Volume I page 34 - IHRF