Words on the Way - Muz Murray Mantra Yoga Master

It is made up of three twisted cotton strands, representing the
three major nadis and the psychic current that opens the third
eye; also the holy trinity Brahma, Vishnu and Shiva, and
various other esoteric threesomes according to different
authorities. Each strand is also made up of another three
strands, making the esoteric number nine, which represents the
Changeless Absolute—Brahman. There are three knots in the
thread, representing the three psychic ‘knots’ (granthis
granthis) within
sushumna nadi, which must be pierced before kundalini is
fully awakened and enlightenment can occur.
The thread is worn over the left shoulder, running across the
chest to the waist on the right side and diagonally across the
back. It indicates that the wearer (theoretically) follows the
virtuous Vedic code of behaviour. The study of the Vedas (the
path of jñåna or wisdom) is believed to be assisted by wearing
this thread, which is said to control and enhance the
functioning of the Surya Nadi or ‘sun channel’ breath, flowing
in the right nostril.
As a sash across the chest of a king or general creates a sense
of command, the mental effect of sensing this slender cotton
‘sash’ is intended to create a spiritual sense of command,
which is essential for the path of jñåna.
Thus the jahnavi or jane¨ is treated with the utmost respect.
When squatting for excretion, for example, it must be kept
undefiled by draping it over the right ear. It is only when
performing rituals such as Pith Tarpana (ancestor worship) that
the thread is worn over the opposite (right) shoulder to the left
waist.
Most Shaivite sannyåsins
discard the thread as a sign of
renouncing the world and caste, although one may see a fair
number who do still retain it. Vaishnavas tend to retain it as a
reminder of religious vows and contend that it should not be
dispensed with until final illumination.
301