Miracles are known in yoga as siddhis; and these siddhis are known as 'ashta siddhis'. Ashta means eight, and the word siddhi means perfection.
First we will deal with siddhis from the point of view of raja yoga. When the mind as a substance merges instantaneously into the object on which it is meditating, there appears a special level of consciousness. The process of merging of the mind is known as 'samyama'. The word samyama generally means control, but in raja yoga samyama means dharana, dhyana and samadhi happening instantaneously, not one after the other.
This samyama can be practised on various objects. If you practise samyama on a person, you can read his thoughts. If you practise samyama on your own reflection in a mirror, you can completely experience disembodiment. You will not see your body in a mirror at all. In the same way, there are many centres on which samyama can be practised according to raja yoga: samyama on the sun, moon, planets, the kurma nadi (the internal thyroid gland area), chakras, on mahatmas, or samyama on a person who is full of vairagya.
From this samyama arises a special level of consciousness, and this level of consciousness is a sudden jump from the present state of mind to a very high level of mind. How to explain this? Supposing here is a dog and he is an incarnation. So, the dog is an incarnation. He dies. There is metamorphosis. He is reborn maybe as a dog or as a horse or as an elephant or something. Then he dies. In about ten, fifteen or twenty incarnations he becomes a man, maybe you or I. Now what happened between that and this? What is that process that continued from the incarnation of a dog to a man? That is called the flow of evolution, and that flow of evolution in yoga is known as samskara pravaha, the flow of the samskaras.
This samskara pravaha, the flow of evolution, took about fifty years, or one hundred years to two hundred years to transform this dog into a man. If you know the laws of that samskara pravaha, maybe you can make that dog a man instantaneously. You can compensate. The same thing happens not only with the human body. It also happens with chemicals, materials and the atomic energy which disintegrates from uranium barium over two and a half million years, yet can be made to disintegrate in five seconds by realizing the entire process.
In the eyes of raja yoga, siddhi is the perfection of mind by compensating the necessary laws that the mind is subjected to in the course of a few thousand years. They are called 'ashta siddhi'. In India, Hanumanji is considered to be the owner and the giver of ashta siddhi: ashta siddhi, nawa nidhi ke data– "the giver of eight siddhis and nine kinds of wealth." Perfection of mind means dissolution of mind completely. It has nothing to do with the ethics and morality of a religion.
According to tantra, siddhi is an expression of the awakening of kundalini. When kundalini awakens, it energizes or awakens each chakra and finally goes to ajna chakra. As and when the chakras are getting awakened, they transmit and manifest their quality through the physical body. You may be a poet or an artist, a speaker or a prophet; you may make predictions or be clairvoyant. Concentration of the mind is considered to be the key behind it.
By birth also, one can be a siddha, from past karma or from one's parents. According to the shastras and scriptures, the conjugal relationship practised through the medium of yoga practices with the attainment of higher buddhi during the relationship, produces a high quality of energy in the sperm, infuses or injects that energy. When the energy level in your body is very high, everything in your body is charged with those extra electrical impulses. So children are born like that. Sant Jnaneshwar, Adi Shankaracharya, and many others at the age of six, eight or ten were brilliant people.
When you are a yoga bhrashta, when your yogic practices remained half-complete or incomplete in the previous birth, and you discarded the physical body, in the next life you are born, according to the traditions, in two types of families. One is a clean, prosperous family, not necessarily very rich, shriman, or the family of yogis who have a higher consciousness.
When you practise siddhis there are negative effects, therefore it is necessary that one should practise yama and niyama before. That is precisely the reason why yama and niyama are prescribed before you take to the practice of yoga. If you are not truthful; if you are not full of love and the spirit of non-violence; if you are not a self-controlled person; if you are a thief, then you are going to project your siddhi to fulfil your personal purposes. If I am angry and we are enemies, then if I have a siddhi I am going to harm you.
Siddhi is the natural evolution and those who practise can get it very easily, but it is advisable that one should not at all work for miracles. In the tantric tradition, these siddhis are attained by awakening kundalini, by invoking the spirits into the body and that's all.
The ashta siddhis are the capacities by which you can control and render your mind to the size of an atom, and the mind can become completely dissolved. Or the mind can be made into a very big object. You can create an elephant or a bigger substance and you can have control over nature. As you know, Lord Krishna created an illusion of darkness after the death of Abhimanyu. Then the Kaurava, Jayadratha, came out and thought that it was already night fall, and suddenly the whole illusion stopped and the sun was shining. So Krishna had control over that.
Whatever you wish must happen. Anima means smallest; mahima, very big, and lahima, very heavy. Hanuman became bigger and bigger.
These siddhis are not to be practised during Kali Yuga. That is what is said, because the minds of people in the Kali Yuga are polluted or vitiated by the lower instincts, like anger, passion and greed. If you get these siddhis you are going to use them for your own interests.
In this Kali Yuga we have the evidence of some small siddhis. From time to time either you take one bread and make it into five thousand; or you walk over the ocean or something like that; or you create this or that. These siddhis, such as clairvoyance, clairaudience, materialization of an object, should only be intended to turn the minds of the people, that is all.
Siddhis have their own limitations, even though they may be played by Krishna or Hanuman. For some time it is good, but people must be properly trained and they must be properly guided.
—23 December 1982, Mani Umrolia's Residence, Mumbai, India