“In introducing the Yoga Sūtra Chapter One Upāya section within verses 20-39,
Krishnamacharya talks about Das Upāya or ten approaches,
of which two are Śodhanam (Purifying) Sādhana
and eight are Śamanam (Palliating) Sādhana.”

“The ten senses or Das Indriya are the gateway between the inner and the outer,
in the twin roads of this phenomena we call experience or action.

The five senses that transport experience from the outer to the inner
are called the Jñāna Indriya, or the senses through which we receive the world.

The five senses that transport actions from the the inner to the outer
are called the Karma Indriya, or the senses through which we put out into the world.

The co-ordinator of this remarkable interface is known as Manas.
The identifier in this remarkable process is known as Ahaṃkāra.
The discerner in this remarkable trinity is known as Buddhi.
The observer in this remarkable play of experience and action is known as Cit or Puruṣa.”