“In introducing the various Upāya offered within
verses 20 to 39 in Yoga Sūtra Chapter One,
Krishnamacharya talks about Das Upāya,
of which two are Śodhanam Sādhana
and eight are Śamanam Sādhana.”
– Paul Harvey on Yoga Sūtra Chapter One verses 20-39

“The Das Indriya or ten senses of experience and action,
whilst seen as belonging to the Bāhya Aṅga or five external limbs
in the eight limb Aṣṭa Aṅga Yoga of Patañjali,
are also the gateway to the Antar Aṅga or three internal limbs.”
– Paul Harvey on Yoga Sūtra Chapter Two verse 54

“The ten senses or Das Indriya are the gateways
between our inner and the outer experiences,
in the twin roads of the worldly phenomena
that we call sensory knowing or bodily action.
The five senses that transport knowing from
the outer to the inner are called the Jñāna Indriya,
or the senses through which we perceive the world.
The five senses that transport action from
the inner to the outer are called the Karma Indriya,
or the senses through which we act out into the world.
The coordinator of this remarkable interface is Manas,
often referred to as the eleventh sense or internal organ.
The identifier in this remarkable process is Ahaṃkāra.
The discerner in this remarkable trinity is Buddhi.
The source of perception within this remarkable play
of knowing and action is known as Cit or Puruṣa.”
– Paul Harvey on Yoga Sūtra Chapter Two verse 54

“Mudrā practice is important since it assists
the ten Prāṇa to move freely in the Nāḍī.”
– T Krishnamacharya introducing Chapter Three in the Gheraṇḍa Saṃhitā

“Prāṇa is the élan vital.
It is the mover and the sustainer of the body in all living beings.
Because of this all pervasive movement and irrepressible vitality,
it is also hard to keep reined in through the ten sensory horses.
When the personalised field of Prāṇa becomes unreined,
it transforms into Vāta and the system becomes disturbed.
The primary practice in Haṭha Yoga to minimise the
conversion of Prāṇa into Vāta is Prāṇāyāma.”
– 108 Yoga Practice Pointers