What develops Sattva ?
The path of liberation starts within. We have potent forces inside, which, if devised wisely can help us control the mind. But, care should be taken that we do not engage in the blind crazy fight, rather skilfully operate these inner forces.
According to Shrimad Bhagwatam:
The gunas, sattva, rajas and tamas, belong to the intellect and not the Self. Through sattva one should subdue the other two and subdue sattva also by means of sattva itself.
Through developed sattva a man attains that form of spirituality which consists in devotion to Me. Through the use of sattvika things (i.e those which lead to purity and illumination) sattva is developed; this leads to spirituality.
That superior form of spirituality which is brought on by an increase of sattva destroys rajas and tamas. And when both of them are destroyed, inequity which has its rise in them is also quickly destroyed.
In the above stated verse we understand a very important fact that spirituality and mind control are identical. So, most important for those who want to learn mind control is to develop sattva.
What develops sattva?
There is an important verse in Gita, which specifies what things make us sattvika:
Scriptures, water, people, place, time, work, birth, meditation, and purification- these are the ten causes which develop the gunas. (Ibid., verse 4)
The objects specified in the verse have their rajasika and tamasika counterparts but when we want to become sattvika, we should choose to avoid them and go for the sattvika counterpart.
The essence of the last verse is:
Only those scriptures are to be followed which teach nivrtti or he march back to the oneness of Brahman, not those that teach pravrtti or continuing the multiplicity (rajasika) or those that teach downright injurious tenets (tamasika).
Similarly holy water only is to be used, not scented water or wine, etc.; one should mix only with spiritual people, not with materially-minded or wicked people.
A solitary place is to be preferred, not a public thoroughfare or a gaming house.
Early morning or some such time is to be selected for meditation in preference to hours likely to cause distraction or dullness.
Obligatory and unselfish works alone should be done, not selfish or harmful ones.
Initiation into pure and non- injurious forms of religion is needed, not those that require much ado or those that are impure and harmful.
Meditation should be on the Lord, not on sense- objects or on enemies with a view to revenge.
Mantras such as Om are to be preferred, not those bringing worldly prosperity or causing injury to others.
Purification of the mind is what we should be interested in, not merely trimming up the body or cleaning up houses. (Ibid., verse 6, Sridhara gloss.)
When preponderance of sattva is achieved by an aspirant through these or other means, the constitution of mind changes; this change in its creative and positive aspect is called inner transformation. Until this is achieved no true work is really done for gaining control over the mind.