Yoga Sūtra Chapter Four verse 20

एक समये चोभयानवधारणम् ॥२०॥

eka-samaye ca-ubhaya-anavadhāraṇam ||20||

And both not ascertained at one juncture.

eka - one; alone, solitary, single, happening only once, that one onlysamaya - circumstances; appointed or proper time; agreement; regulateca - andubhaya - bothanavadhāraṇa - not ascertained

Commentaries and Reflections

Commentary by S Ramaswami:

“Again an argument to reinforce the idea that the observer has to be distinct from the observed.
The Citta, because it is an object, cannot observe itself and another object at the same time.
Thus the Citta is limited.
The argument in this Sūtra is as if the mind is called self-luminous, it will be both the knower and the knowable and it would imply cognisance of two things at the same time. But as this does not happen, the mind is not self-luminous.”