Sādhanā is of various kinds in Tantra. However, in essence, the primary goal of tāntrika sādhanā is Bindu-siddhi. The Buddhists term the Bindu as Bodhicitta and this is associated with the Manōmaya kōśa whose essence is the mind. The essence of Prāṇamaya kōśa is prāṇa or ōjas, whereas that of Annamaya kōśa is vīrya or śukra dhātu. In an ignorant or paśu sādhaka, these three are unsteady (chanchala) and unrefined (malina). Based on the prasthānabhēda of sādhanā, some approach the mind, some others the prāna and some, the Bindu. By the effect of yogic kriyā, the Bindu attains purity (nirmalatā) and sthiratā (steadiness).
In the Vedic age, the secret of Bindu sādhanā was awarded utmost importance during the stages of Brahmacarya and Gārhasthya āśramas. The goal of Brahmacharya was to attain Bindu śōdhana and Bindu pratiṣṭhā. During this stage, all types of Bindu kṣōbha were prohibited as chyuti or patana of Bindu was considered equal to death:
maraṇaṁ bindupātēna jīvanaṁ bindudhāraṇāt |
If a yogin accomplishes dhāraṇā of the Bindu and its ūrdhvagamana, he attains the siddhi of amaratva (immorality). The necessary condition for attaining the state of ūrdhvarētā is ūrdhvagāmitva of the Bindu. An ūrdhvarētā puruṣa is ever established in the state of divinity and Brahmavidyā.
In the case of Gr̥hasthāśrama, this sādhanā was accomplished with the partnership of one’s Dharmapatnī:
sastrīkō dharmamācarēt |
For such a Gr̥hastha, pārivārika jīvana was helpful towards rasa sādhanā. However, for a naiṣṭhika brahmacārin, samyama and kaṭhōra brahmacarya are the approaches to accomplish rasa sādhanā, and nothing else. The mahāsukha sādhanā of the Buddhists is simply a part of this gupta rasa sādhanā. Aupaniṣada sādhanā illustrates the famed Pañcāgni vidyā, where starting with Annamaya kōśa to ānandamaya kōśa, ūrdhvagati is accomplished by offering āhuti into various Agnis. At each stage, the sattva-vastu or sārāmśa therein is offered to the fire at the same stage, as a result of which purity is attained and ūrdhvōnmukhatā is achieved. Eventually, after the various stages, the śuddhi is completed when no mala remains and at this stage, there remains no need for any more āhuti. The need for a fire is also dropped then. At this stage, vishuddha amrita is obtained. Technically, at each of the five stages, five kinds of nectars are obtained, but the fifth amr̥ta is considered the most important as it is the upādāna and upajīvya of ānandamaya kōśa.
Those in Bhakti mārga do not discard this amr̥ta. This is indeed Bhaktirasa, prēma, etc. The dispassionate jñānī however exhibits vairāgya even towards this amr̥ta and remains immersed in svasvarūpa alone.
In the scheme of Tantric sādhanā, in the initial stages of paśu bhāva, samyama, brahmacarya, yama, niyama, etc, are considered to be absolutely necessary. In this bhūmi, the Bindu attains śuddhi and sthiratā. After this stage, having attained vīra bhāva, one attains adhikāra for Prakr̥ti samyōga or prakr̥ti sambhōga as may be the case. The vīratva in this stage is necessary on account of the samgharṣa of puruṣa with prakr̥ti. Siddhi of vīratva lies in the victory of puruṣa over prakr̥ti. The vīra stations himself as the svāmī, bhartā or adhiṣṭhātā of Prakr̥ti. If a sādhaka is unable to conquer prakr̥ti, he is considered fallen, a bhraṣṭa sādhaka. After successfully attaining vīrabhāva, sādhaka attains sahayoga with prakr̥ti, gradually attaining divyabhāva. In the state of divyabhāva, there is only pūrṇādvaita and not a trace of dvaita.
Like it is important to let go of prakr̥ti in the first stage, during the second stage when yōgyatālābha is attained, it becomes essential to undertake the grahaṇa of prakr̥ti. In the third stage, there is neither grahaṇa nor tyāga. At this juncture, both puruṣa and prakr̥ti attain a combinational harmony and enter an akhaṇḍa sattā. At this stage, there remains no separateness between puruṣa and prakr̥ti. This indeed is the sāmarasya of śiva and śakti.
Bindu sādhanā of the Buddhists is, in essence, a branch of rasa sādhanā. After the udbhava of Bindu, to prevent the patana of the Bindu or the skhalana of the vajramaṇi, it is to be protected within the Nirmāṇacakra situated at the navel. Though Bindu is mercurial in nature, yogic kriyā is employed to make it steady. This is called chanchala bindu or savr̥ta bodhichitta. When made stable through yoga, it comes to be called vivr̥ta bodhichitta. When bodhichitta becomes vivr̥ta, then it transforms into mahāsukha. Thus, the essence of annamaya kōśa (śukra bindu), transforms into the paramānanda of ānandamaya kōśa. In other words, kundapuṣanibha savr̥ta bōdhicitta attains ūrdhvagati to transform into mahāsukha. It must thus carefully be noted that only within the mahāsukhacakra or uṣṇīśakamala does the Bindu remain steady, not in any other place.
The Buddhist Tantras have used ṣaḍaṅga yōga of the Nātha sampradāya in many ways. ṣaḍaṅga yōga, while prominent in Nātha sampradāya, was also adopted by the ancient Vaiṣṇavas as stated by Bhāskarācārya in his Gītābhāṣya. Guhyasamāja and Sēkōddēśa ṭīkā list six of these: pratyāhāra, dhyāna, dhāraṇā, anusmr̥ti and samādhi. It is well-known that the carama lakṣya of a yogin is the attainment of nirāvaraṇa prakāśa. This carama lakṣya cannot be attained with any of the āvaraṇas existent in perception. The tantra propounds that mukti from all āvaraṇas is through the awakening of the prabhāmaṇḍala and the yogi’s entrance into this maṇḍala. However, entering the prabhāmaṇḍala is not an easy task even for the greatest of yogis. Till an avasthā named Vajrasattva is not attained, entry into prabhāmaṇḍala is impossible. Without the accomplishment of bodhichitta, Vajrasattva avasthā cannot be attained. For becoming a Bodhisattva, abhijñā pañcaka is a necessity and abhijñā will not arise till mantra siddhi is attained. Thus, the Tāntrik yogin first begins to accomplish mantra siddhi, which is attained through the first yōgāṅga named pratyāhāra. Then, through dhyāna, abhijñā is awakened. The bhāva of the Bodhisattva is attained through prāṇāyāma and dhāraṇā grants the Vajrasattva-bhūmi. Anusmr̥ti has its fruit in the entering of the prabhāmaṇḍala and the fruit of the sixth and final yoga of samādhi is the dissolution of all āvaraṇas.
Bindu needs to be awakened and brought from Nirṁāṇacakra to uṣṇīśakamala. The udbodha of the Bindu and the awakening of Kuṇḍalinī are essentially the same, described differently in āstika and nāastika parlances. The Buddhists term this as the awakening of svaśakti cāṇḍālinī of the Nirmāṇacakra. The moment cāṇḍālī awakens, the chandra-bindu on the head begins to secrete amrr̥ta.
The knowers of the secret of Kāmakalā explain that when agni and soma are brought together, due to the heat of the agni, the soma bindu begins to swell and secretes amr̥ta. As explained in Haṭha yōga śāstra, the sōmadhārā falls into agnikuṇḍa and burns away, resulting in dēhakṣaya, jarā, vikāra and mr̥tyu. If the yogin prevents the burning away of the amr̥ta through techniques such as the Khēcarī mudrā and ingests the amr̥ta, his physical body is enriched by Chandrakalā and kāyākalpa is accomplished.
While skhalana of Bindu from Nirmāṇacakra downwards can result in a physical being, its ūrdhvagati facilitates the path of nimnasr̥ṣṭi. The Bindu within the Nirmāṇacakra is pañcabhūtātmaka but predominance is of pr̥thvī tattva. Thus, it displays an affinity towards downward skhalana. However, when Bindu becomes ūrdhvōnmukha, predominance is of jala tattva into which the pr̥thvī tattva dissolves. The solidity or rigidity of the Bindu is lost and it moves upwards. After raising further, the predominance of tejas tattva takes over and jala tattva dries up. It consequentially becomes ākāśa pradhāna (and finally chitta or jyoti pradhāna), merging into uṣṇīśakamala. After the Bindu becomes stationed on the uṣṇīśakamala, the body of the upāsaka becomes Siddhavajra, and he is blessed with divyadr̥ṣṭi and divyaśruti.
While ārōhaṇa of the Bindu is of great importance, avarōhaṇa is equally important. Without the śuddhi of the Bindu, there is no possibility of śuddha dēha or jnānadēha or baindava śarīra.