Mandukya Upanishad Class 48

Nidhithyasanam is not relevant for
manda and uthama adhikari.  It is meant
for madhyama adhikari.  Nidhithyasanam is
dwelling on the teaching received by sravanam and mananm.  Dwelling is
only mental process and the physical posture is not relevant.  For upasana
physical posture is important, but it is not important for nidhithyasanam. 
In formal nidhidhyasanam one can give importance to physical posture like asana
etc.  This is called Samadhi abyasaha or vedantic meditation; Vedantic
meditation in which yogic stages of meditation are employed.  Yoga sasthra
of Patanjalai has prescribed in many stages (yama and niyama are the first
two):

1. Asana: sit in proper posture
2. Pranamaya: breath properly to quieten the mind
3. Pratyahara: control sensory inputs
4. Dharana: withdraw into one’s own self
5. Dhyana: meditate
6. Samadhi

This vedantic meditation is not compulsory,
but one can chose to do this if one finds it useful.

Number 5 dhyana can be:

1. Paramatma Dyanam:  You can meditate up on Brahman as sathyam; this is existence meditation
2. Jivatma Dhyanam:  Meditate up on all pervading existence present in this body mind complex also, available as sat as well chith the consciousness also.  This is consciousness meditation.
3. Anatma mithyatha dhyanam:  Meditate up on any object on the creation.  When anatma is mediate up on see it as mithya nama roopa
   1. Atma sathyaha
   2. Atma nithyaha
   3. Atma niviharah
   4. Atma sudhaha
   5. Atma asangaha

This is called dharana or samadhi
abyasa.  The purpose of this samadhi abyasa is

1. Samadhi abyasa is not meant for moksha; moksha is not the result of mediation; moksha is already your swaroopam. Nidhidhyasanam is not for moksha
2. Samadhi abyasa is not meant for gyanam.  Knowledge can be gained only through one of pramanam;  Source of knowledge guru sasthra upadesa sravanam.
3. Samadhi abyasa is not meant to give any extra ordinary experience to confirm vedantic teaching

Patanjali who prescribed this yoga
sastra for nirvikalapa samadhi, said dwaidam is reality.  Nirvikalpa
samadhi will not prove advaidam or moksha.  Advida gyanam gained only through
vedanta sravanam gets assimilated when you keep in mind without any
distraction.

When a person practices this
vedantic meditation, this meditator will face certain obstacles called dhyana
pradhibandha.  Gowdabahda does not discuss the stages of meditation; these
are discussed in Chapter 6 of Baghawad Gita; however, Gowdabadha discusses the
four obstacles to Nidhithyasanam:

1. Layaha:  Sleep, dullness of mind, tamasic condition;
2. Vikshebaha:  Restlessness or wandering mind; rajasic condition;
3. Kashayaha:  Stagnation of the mind; mind is neither sleeping or wandering; not available for meditation.  This happens when there are deep internal disturbances.
4. Rasaswadhaha:  Rasaha means anandaha; if a person is successful in relaxing the mind, the mind enjoys certain happiness.  This is available at the time of relaxation which is temporary; because it is dependent on the mental state of withdrawn and relaxed.   This is comparable to sense pleasure because both are temporary.  Since it is temporary, it is also samsaram.  This becomes an addiction and dependence.  therefore, enjoying this temporary pleasure is also an obstacle to assimilation of vedantic teaching.

Gowdabadha and other commentators
have prescribed remedies for these obstacles in verses 42 to 45

1. Gowdabadha does not give remedy for layaha; one of the commentators has suggested to remove the cause for sleep; Causes for sleep
   1. Nidhra sesha:  If you don’t give enough time for sleep; Don’t have sleep back log
   2. Ajeernam; dullness of stomach; dysfunction of body;
   3. Baghu asanam; overeating.
   4. Samah:  Extra physical activities;
2. One of the main causes for restlessness is attachment.  Raga towards the external world; remedy:
   1. Develop vyragyam; by repeatedly reminding that raga and attachment is the cause of sorrow. Raga will lead to soha
   2. Abyasaha:  By dwelling up on the teaching learn that there is no world at all other than atma.  See the world either as nonexistent or see it as a source of sorrow;
3. There is no solution for kashayaha; remain in sakshi bava; remind that mind is a source of disturbance.
4. Remove rasawadhaha telling your intellect that any temporary pleasure is samsara and not atma swaroopam, because it is available only during meditation.

Verse 43

Remedy for viskheba is provided in
this verse; remedy for disturbances from external world.

1. Vyragyam method:  See the attachment to the world as a cause for pain.  This is called dhosha dharsanam.  Repeatedly remind yourself what the attachment will do; turn your mind away from sense objects.
2. Brahma abysa method:  Brahman is alone is the cause and everything else is effect; effect is nothing but nama roopa super imposed on the cause.