Yoga can be seen in three ways: the modern way, where it is seen as a holistic therapy for all physical and mental problems; the upanishadic way elaborated in the Bhagwad Gita, where it is an intellectual, emotional and social technique for self-realisation; and finally the Siddha way where it is a means to attain supernatural powers. This third method is rarely talked about, yet traditionally for most Indians, until recent times this aspect of yoga was most familiar.
A jogi was a wandering holy man, ascetic and alchemist, mendicant and magician, all rolled into one. These magical powers were related to his celibacy and sensory continence. He was called a Siddha Jogi, one who is accomplished. He had the power to change shape and size at will, fly in the air, walk on water, create food out of thin air, control birds and beasts, heal the sick, save people from snake bites, make the earth fertile, enable barren women to bear children, tolerate extremes of temperature, summon gods and demons at will, bring the dead back to life. He was seen riding tigers and peacocks and bulls, or sitting still on mountaintops or meditating in caves.
Today, jogis who claim such powers are called tantrics at best and charlatans at worst. This does not stop thousands of devotees from flocking to their monasteries (if they are alive) and shrines (if they are dead), seeking holy ash believed to possess magical healing powers.
Yoga and tantra have much in common. Both believe in the primary divide between Purusha human consciousness, and Prakriti, nature. While yoga seeks Prakriti as inanimate, tantra considers Prakriti to be animate with a will of its own, which is why in tantra, nature is addressed as shakti or goddess, while in yoga, nature is maya or delusion whose spell has to be broken. While a follower of tantra seeks power over nature, the follower of yoga seeks liberation from nature. This makes the tantric a sorcerer and the yogi a mystic. The lines are often blurred.
The man who made the secrets of tantra and yoga accessible to the common man is Gorakhnath. Until his arrival, this was a secret doctrine that was revealed only to those who had been initiated into the Nath Panthi order. Not much is known about the Nath Panthis and their doctrine. What is known comes from folk legends, as the Nath Panthis preferred the oral to the written tradition.