Lord Krishna in Bhagavad Gita Chapter 4, mentions 12 types of powerful spiritual sadhana's (spiritual practices or yajnas) one can choose to purify one's mind and strengthen one's relationship with the Lord.
Their end result (karma-phala) can be compared to washing a dirty car (mind) with a hose (sadhana).
Yes, the car will attract new dirt sooner or later the more it moves or engages in the world (EG: friends, news, people's opinions, etc).
For this reason, common mistake within spiritual world is to endlessly purify one's mind. We call this “stuck in sattva“.
Sattva feels fulfilling. One experiences peacefulness and is generally happy about everything. Then mistakes this feeling as Enlightenment.
How to know if you're “stuck in sattva”?
Spiritual practices are diligently performed to get something out of it. Like more peace of mind, sharpness, clarity, calmness.
One ends up depending on yet another worldly object, no different then child depends on his/her toys for it's well-being. Except object is different, but problem is same; dependence.
In reality, feeling top of the world or in spiritual ecstasy has NOTHING to do with Enlightenment. But everything to do with a purified-peaceful mind.
Atma (consciousness, or Self) and mind are two different orders of reality. Thus how one's body-mind feels is not-I (anatma).
It's unfortunate most spiritual seekers unsuspectingly subscribe to notion of “Experiential Enlightenment”, attempting to experience transcendence or higher states of consciousness.
In summary: Mind with little to no thoughts just means a mind that's clear/pure. That's it! It doesn't mean ignorance of “I” is resolved. In fact a jñāni (wise person) couldn't care less whether his/her mind is undergoing a torrential storm or it's quiet. The mind is NOT-I. Thus jnani won't even need nor have inclination to say “I have a clear mind”.
What is the purpose of spiritual sadhana? Purify the mind.
Because it makes contemplation/self-enquiry meaningful and fruitful under guidance of a guru (teacher of Vedanta), whose using a proven means of knowledge (pramana) to help remove ignorance preventing you from recognizing your limitless nature.
Thereby shifting “I” from body-mind to Consciousness.
After this, one has accomplished all there is to accomplish on Earth. It's their last lifetime here.
Body will die when prārabdha karma is over (meaning body dies when unfinished business is finished in this lifetime). Then there's no more rebirth.
So order is: sādhana > jñāna-yoga > mokṣa
Now that we have clarified purpose of sadhana, let's get into them below. But before we do…
You'll see word yajña below. It means “Ritualistic fire worship”.
In context of the list, it also means spiritual practice whose purpose is two fold:
- Purify and ready the mind for Self-Knowledge (jnana-yoga).
- Dissolve false difference between individual “I” and Brahman.
Here they are…
- Daiva-yajña: This spiritual practice involves propitiating the presiding deities by offering various materials into the sacrificial fire chanting various mantras (4.25).
- Brahma-yajña: This spiritual practice involves offering of oneself into the fire of the supreme Truth (Brahman). This means to meditate on the supreme Truth as being one with the pure Self. Such practice of meditation (brahma-abhyāsa) leads one to the Realisation ‘I am the supreme infinite Truth.’ (4.25)
- Indriya-yajña: Herein the various sense objects (sounds, touch, forms, tastes and smells) are offered to the sense organs of perception (hearing, touching, seeing, tasting and smelling) which in turn are offered to the fire of control. This means to control one’s sense intake, take in only what is conducive (sāttvika) and that too as an act of worship (4.26). For example, the eyes feast on the glorious form of the Lord or the ears listen to music that quietens the mind. Spoken in the language of negation it means ‘see no evil, hear no evil and speak no evil’ as depicted by the famous three monkeys. In the language of assertion it translates as, ‘May we hear auspicious words through our ears and see auspicious sights by the eyes.’
- Saṃyama-yajña: This is to offer all the sense organs of perception and action along with the physiological functions (prāṇa-karma) into the fire of self control (4.27). This meditation practice elaborated in the Gītā, Chapter 6, involves the total withdrawal of the senses from all external pursuits (pratyāhāra) and focusing the controlled mind on the Self.
- Dravya-yajña: This involves offering material (cash or kind) to the needy (4.28). Social work and charity are also considered spiritual practices of a high order when done as an act of worship of the Lord. Herein the needy one is considered the form of the Lord Himself (daridra-nārāyaṇa).
- Tapo-yajna: Living an austere and simple life, or performing special austerities like fasting are spiritual practices which help to conserve our time and energy and increase our endurance and control. (4.28)
- Yoga-yajña: This refers to the eight-fold steps of: (1) yama: practicing values like non-injury, (2) niyama: taking vows like purity of body and mind, (3) āsana: practice of postures, (4) prāṇāyāma: breath control exercises, (5) pratyāhāra: withdrawal of senses, (6) dhāraṇā: practicing concentration, (7) dhyāna: practice of meditation, and (8) samādhi: practicing total absorption of the mind. (4.28). Yoga is in vogue all over the world, but generally understood only as the practice of postures, that too done for health purposes. This, however, is a spiritual practice which can lead us to the highest Realization when practiced rightly and regularly.
- Svādhyāya-yajña: This can be understood as the spiritual practice of reading of the scriptures (pārāyaṇa) or repetition of a mantra (japa) or study of the scripture (svādhyāya) or introspection (sva-adhyayana) (4.28).
- Jñāna-yajña: This is the spiritual practice of understanding the scriptures through listening to discourses, self study or in groups (4.28).
- Vrata-yajna: Involves taking up special vows which help sharpen one’s mind and senses (4.28).
- Prāṇāyāma-yajña: This spiritual practice has to be done under the guidance of an experienced practitioner. It involves the control of inhalation (pūraka), exhalation (recaka), and also the holding of the breath outside or inside us (kumbhaka) (4.28).
- āhāra-yajña: This means to offer right food in the right quantity for the digestive fire (4.30). Controlled eating by itself becomes a spiritual practice when done as an offering. This can be done by all each day at each meal time. Uncontrolled eating is the cause for obesity and many diseases.
Number 2 and 9 is jnana-yoga, which is taught here.