“Ekāgratā is compared to the sharp tip
of the steady flame of a Ghee Lamp
when not exposed to any wind.
In other words,
the mind should not move
anywhere else other than in the
direction fixed for Dhāraṇā.
Obviously the Viṣaya for Dhāraṇā
and Dhyānam should be the same.
The stronger the Dhāraṇā,
the steadier the Dhyānam.”
– T Krishnamacharya on Bhagavad Gītā Chapter Six verse 19

“The fourth way the mind functions is called Ekāgratā.
Here clarity has come about
and we have direction and are able to proceed.
What we want to do is much clearer
and distractions hardly matter.
This is also called Dhāraṇā which was explained earlier.
Yoga is actually the beginning of Ekāgratā.
Yoga suggest means to create conditions that gradually
move the Kṣipta level of mind towards Ekāgratā.”
– TKV Desikachar Religiousness in Yoga
‘The Way the Mind Functions and the Concept of Nirodha’
Chapter Eighteen Page 251