How subtle can the focus be, and is there a limit to the mind’s ability to understand?
Yogasūtra I.45 - sūkṣma-viṣayatvaṁ ca-aliṅga-paryavasānam
The extent of subtle perception includes all levels of creation to the limit of the Guṇa-s.
However, the mind cannot comprehend the very source of perception within us.