Yoga Sūtra Chapter Two verse 47
When working with the Breath in Āsana its perhaps less appealing initially,
but ultimately more attractive, satisfactory and effective,
to integrate a focus of Samāpatti (Unity) of
Śaithilya (Relaxation) in Ananta (the Infinite),
through a developmental Sādhana (Means to Accomplish)
on the Siddhi (accomplishment) of Dīrgha or Length,
supported by Sūkṣma or Subtlety.
From Yoga Sūtra Chapter Two verse 47 T Krishnamacharya taught that:
– the common denominator for successfully uniting (Samāpatti)
both (Bhyām) aspects of relaxation (Śaithilya) and the infinite (Ananta)
within the practice of Āsana is the Breath.
He saw it as Prayatna (continued effort)
and synonymous with Jīvana (giving life).
The continued effort of the Breath is that which gives life.