Tantra, though said to have been revealed for the Kali Yuga, is in essence a timeless doctrine, and it is to this perennial spiritual heritage that both yoga and alchemy rightfully belong. Tantra is that system which liberates energy and expands consciousness. Consciousness expansion takes place by the removal of obstructing factors which yoga terms kleshas and alchemy calls dross. Afflictions viewed from the point of alchemy constitute those corrosive properties that rust the personality-complex.
While in the alchemical sense 'transmutations' are those changes which occur at the physico-chemical level, 'transformations' are those which are noticed at the psycho-spiritual plane. Hence alchemy as a science which transmutes the base metals into gold has to be understood in the light of this dual metamorphosis. Making gold by their 'art' meant the process by which man's consciousness would be raised to finer states of responsiveness. As in the transmutation of 'base' substances to 'noble' ones, occurring in the mineralogical domain, so also in the human context it was through the purification of psycho-physical vehicles that man was said to have taken a step ahead in the evolution of his consciousness.
Alchemists not only considered matter 'alive' but also potent with force, as shakti in the tantric tradition. Hence nature did not exist as a dead matter 'out there' but was animated and behind the multiplicity of forms lay the unity of its essence. The alchemists' efforts were then directed towards the discovery, awakening and further utilisation of those subtle energies.
The Great Work of the alchemists, called Opus, begins by the systematic application of the methods and procedures which encompass the external transmutations and are in a way simultaneously interiorised. Alchemists were not passive observers of the objective phenomena but rather, sympathetic and active participators in all that happened not only in the outer chemistry but also in the 'inner chemistry' of their psyche. Theirs is a quest for forces operative at both levels, like the yogis for whom nature was a field of observation, from which they gained insights which they then proceeded to apply on themselves. Thus their bodies for them came to constitute a field of experimentation.
Alchemy is filled with references to fire and in all the alchemical pictures we notice furnaces of all kinds. Alchemists are also reported to have kept vigil for days in front of their fire furnaces. This could be well compared with such rites as of sitting between five fires (panchagnitapah) and other yogic tantric rituals. Fire is a very important purifying medium (also among Zoroastrians and Vedic people) and parallels between alchemy and yoga in this connection further illuminate their close affinity. Tapas is a yogic term, which applies to all those disciplinary processes which are ascetic in nature, the ultimate aim of which is said to be the burning of all the internal impurities or the accumulated store of karmas (for which birth in human form is a privilege as it provides great opportunities for their eradication and ultimate exhaustion). It is also stated that the dawning of spiritual realisation (gyana) acts like fire, burning all the karmic pollutions within the inner anatomy of the individual. In yoga, the heat generated through the techniques of pranayama are not only of a physical nature, but are psychic or, as some put it, of 'mystical nature'. In Manu's words, "As baser things mixed with gold and other metals are removed by burning those metals, so the propensities of the senses are removed by pranayama."
The symbolism of fire as a purifying medium can also be seen in the alchemical sketches. In one of them by a seventeenth century alchemist, we see a dead king being eaten by a wolf, and in the background we notice a big fire from which the king emerges unhurt while the wolf burns in the flames. This symbolically interpreted expresses the fact that lower tendencies (here represented by the wolf) are purged and hence his consciousness is ultimately sublimated.
The principle of polarity occupies an important place in both the sciences of yoga and alchemy as also in many other traditions. In other words they are androgynous in nature. In yoga besides Shiva-Shakti (consciousness-energy), we have the ida-pingala nadis which are lunar and solar respectively. The name hatha yoga is a combination of 'ha' meaning the sun and 'tha' meaning the moon and the corresponding terrestrial metals, namely gold and silver, upon which they exert influence. The alchemical androgynous consciousness, much like yoga, is indicative of the principles of the active-dynamic male and the passive-magnetic female. From their union occurs a sacred marriage or the union of the opposites (coincidentia oppositorum). This is known as conjunction in alchemy and could be confidently referred to as 'yoga' from the Sanskrit 'yug' meaning union or yoking.
Both the sciences aim at resolving the splits in the human personality and at restoring holisticity (which is believed to have prevailed at the Golden age or Satya yuga, and in the biblical pre-fall state). Their final goal is to render personality 'indivisible' or whole. Hence the individual is no more a 'divided self but an integrated being (from latin 'integer' meaning complete or whole). This holisticity is achieved through the transformative techniques constituting the sadhana of these sciences.
Alchemists always remained acutely conscious of and constantly prayerful to the Divine. This is seen by their statements such as 'if God wishes' (Deo concedente) and also by their kneeling postures, in various alchemical drawings. In all accounts alchemy was never considered to have been a human creation but as a divinely inspired science much like yoga, which was said to have been revealed by Lord Shiva himself. The spiritual nature becomes clear from the fact that alchemical ideas are found in China within the Taoist literature, in Egypt in close connection with the Jewish Kabbalah, and the Greek Mystery traditions.
The history of alchemy reveals the existence of secret societies, the entry to which was barred to the uninitiated. In order to qualify as a member, the neophyte was examined carefully and made to go through rigorous tests, after which a ceremony was conducted wherein the secrets of the art were transmitted to him. The reason for this selectivity was that only the competent (adhikari) should get access to this carefully guarded tradition, lest it were adversely affected and its techniques misused. Hence alchemy was a secret as well as a sacred science and not a venture merely aimed at making gold out of base metals and minting money, as it were.
In general alchemists did remain detached much like the yogis. And we need to add that reference here is to 'true alchemists' for there were many false ones, who, like bogus yogis, brought a bad reputation to the systems. It seems, much like magic or even tantra, that there existed two forms of alchemy, black and white. The so-called white alchemy was the painstaking result of those men who were seers with 'great insight into the human soul, and were also first rate scientists who did not ignore experimentation at the cost of speculation. Along with their theoretical expositions one comes across systematic methods for application. It is here that both alchemy and yoga could be said to be systems of Applied spirituality'.
It is also important to bear in mind that alchemy, within this definition, acquires a greater dimension which is 'alchemystical', denoting clearly its physio-psychic nature. Both the sciences have their corpus, anima and spiritus. The body of yoga is formed of the asana, kriya, etc., while the body of alchemy is the experimentations with various elements. Their psycho-spiritual dimension is treated through their sadhana which consists of processes for mental purification and also of meditational techniques. However, unlike yoga little is available of similar alchemical practices, but even then it is possible to put the pieces together and get an idea of methods they used. For example the regular, rhythmic breathing was an essential feature of the Taoist alchemical discipline. Also there are signs which show that the subtle essences of the elements under experimentation were meditated upon, and this matches perfectly with the samyama technique of Patanjali.
Symbols of alchemy and yoga bear striking resemblances. The snake kundalini (which according to Shiva Samhita, holds her tail in her mouth) finds its alchemical equivalent in uroboros, a serpent with a dragon like head, biting its tail. Then we have the two interlaced triangles which signify the alchemical opus and the very same symbol stands for the chakra of the heart indicating that the heart has been a spiritual kaaba not only for the Sufis but for others too, "Within the heart lotus," declares Taittiriyopanishad, "is an ethereal space, in which the immortal, resplendent Lord of mind resides...". The next similar symbol is the twisted snakes on the caduceus of physicians. This is a symbol for health (also found in alchemy), and is the tantric ida-pingala nadis coiled around sushumna. And interestingly enough, in both cases, the two snakes or the nadis cross one another the same number of times. The chakra lotuses of tantra are found in the seven-petalled roses of alchemy. And still more similar symbols could be cited. Symbols in both the sciences are means for perceiving significance and finding the multiple meanings lying under the multitude of forms.
Both yoga and alchemy deal with questions of ultimate concern. Their experimentations (which reveal that they are not speculative theoreticians sitting on a chair on the periphery of life) are blue-prints for the elimination of obstructions which are in the meantime 'obscurations' veiling the Real. Both these 'sciences of man' are best represented by a bridge which leads from a limited and shrunken to a widened and deepened consciousness. Yet neither merely seeks the beyond. For while both are firmly rooted in the phenomenal world, they have their extension into the transcendental realm. In the final analysis the question is not in living in 'this' or 'that' world but in living" intelligently and with total awareness. And it is towards this direction that both alchemy and yoga direct their efforts. For as the Buddhists have rightly observed, "samsara is nirvana" after all.