Yoga Sūtra Chapter Three verse 2

तत्र प्रत्ययैकतानता ध्यानम् ॥२॥

tatra pratyaya-ekatānatā dhyānam ||2||

There, the continuity of psychic activity is meditation.

tatra - in that place, there; thither, to that place; in that, therein, in that case, on that occasion, under those circumstances, then, thereforepratyaya - psychic activity; cause; conception, assumption, notion, idea; ground, basis, motive or cause of anythingekatānatā - continuitydhyāna - meditation, thought, reflection; visualisation; mental representation of the personal attributes of a deity; profound and abstract religious meditation

Commentaries and Reflections

Commentary by T Krishnamacharya:

“The state of Dhyānam is possible in a seated posture.
If a person lies down, it may induce sleep.
If a person walks and moves about,
he may be distracted by the objects around him.
This posture must be in a place
where the mind will not be distracted.”

Dhyānam is an activity of a mind
dominated by Sattva linked to Ātma.
So Ātma and Sattva required for Dhyānam to occur.”

“A person who is physically fit and
who has been cleansed by the Agni of Dhyānam
has no fear of sickness, disease, age or death.”

Commentary by TKV Desikachar:

“Prāṇāyāma leads to this.
Pratyāhāra, to see without the senses distracting or pulling the mind, and
Dhāraṇā, to see without the mind losing itself, because of colouring or expectations.
Dhyānam arises out of this.”

“Perhaps the best explanation of Dhyāna is given by Patañjali in the Yoga Sūtra Chapter Three verses One and Two, where he states that one must first fix the question (Dhāraṇā) and then link to it (Dhyāna).
One who is not able to fix the question is not able to succeed in Dhyāna.”

Meditation can’t be taught,
but can be learnt.”

‎”Meditation is not a technique,
it is a journey.”

“To practice Dhyāna
there are two questions
we need to ask,
Can I hold an object?
Can I sustain that hold?”

Dhyāna is not simply to still the mind.
It involves our ability to reflect afresh,
to discover what we had not known before.”

“How can we distinguish
the actual state of Dhyāna
from infatuation with an object
that pleases and fills the mind?”

Commentary by Paul Harvey:

Dhāraṇā is the process of ‘holding onto’ the object.
Dhyānā is the process of ‘linking with’ the object.
Samādhi is the process of ‘integration into’ the object.”

“To hold the Citta for connective moments is Dhāraṇā.
To be held by the Citta for connective moments is Dhyānam

Dhyānam is the art of cultivating
a continuity of presence within
the activities in the psyche.”

“Finally, the consideration of movement
or stasis sits within a relationship to the
deeper purpose of Āsana within our journey
through the body and the breath, to the mind
and beyond, through considerations such as:
In relation to the psychological ideal of remaining there.
According to the definition in  Chapter Three verse 2 of
the Yoga Sūtra, a continuity of psychic activity is the ideal.
This is seen as the ability to stay, as if in the same moment, as
one moment melds into the next moment and the next moment.
In other words, the ability to internally maintain a continuity of
experience as if maintaining an apparent stillness of movement.
Access to such subtle states requires a containment of movement
that ultimately extends from the body to the breath to the mind.”

Dhyānam is both a Sādhana and a Siddhi.
In that, it is a Siddhi of Dhāraṇā,
as well as a Sādhana for Samādhi.”