“From this, the role of senses and sense objects
in causing a ground for disease becomes evident.
They are chiefly responsible for creating disturbance in the mind.
Hence the value of Vairāgya insisted as an aid to help the student.
Otherwise the whole system is sure to reach a state of chaos
because of the erratic movement of vital energy all over the body.
To put it another way, disease results from excess of contact
with objects not conducive to the individual system.”
– T Krishnamacharya on Yoga Sūtra Chapter One verse 34

“The mutual aim of Yoga and Sāṃkhya is to
experience the more discerning aspects of the psyche,
rather than just the more grasping aspects of the psyche.
In the former, the tendency of the Buddhi to discern discriminately
prevails over the tendency of Ahaṃkāra to grasp indiscriminately.
In the latter, the tendency of the Ahaṃkāra to grasp indiscriminately
prevails over the tendency of the Buddhi to discern discriminately.
The former is a state known as Buddhi Sattva,
where the clarity of discernment prevails over the
indiscriminate grasping nature of the Ahaṃkāra.
The latter is a state of Buddhi Tamas,
where the discerning clarity of the Buddhi
is obscured by the grasping nature of the Ahaṃkāra.
Thus our Yoga Sādhana has but one primary Saṃkalpa,
that of the reduction of the obscuration by Tamas in the Buddhi.
This reduction of Tamas facilitates the advent of the clarity of Sattva,
as in the metaphor of the reduction of the cloud facilitates the advent of the sun.”
– Paul Harvey on Yoga Sūtra Chapter Three verse 49