This Self hidden in all beings does not shine. But by seers of subtle n pointed intellect capable of perceiving subtle objects, It is seen.

There is nothing subtler than Purusha. That is the end, that is the supreme goal. 1-III-11 – Yama to Nachiketa in Katho Upanishad

The un-manifested (avyakta) is subtler than Mahat (Hiranyagarbha) n subtler than the un-manifested is Purusha. 1-III-11 – Katho Upanishad

But intellect is subtler than mind and subtler than intellect is Mahat (the Hiranyagarbha). -Yama to Nachiketa in Katho Upanishad, 1-III-10

Sensory objects are subtler than senses n subtler than the sensory objects is mind. Yama to Nachiketa in Katho Upanishad- 1-III-10

But one who has a discriminating intellect as his driver n a controlled-mind as reins, reaches end of the path -that supreme state of Vishnu

But whoso is possessed of a discriminating intellect n a restrained mind, n is ever pure, attains that goal from which he is not born again

‘I found these energies are transformable to love.’ groundreport.com/meditation-reg…

But whoso is devoid of a discriminating intellect, possessed of an unrestrained mind n is ever impure, goes to samsara, not attaining goal.

But whoso is discriminative and possessed of a mind ever collected – his senses are controllable like the good horses of a driver.