Sri Aurobindo
Letters of Sri Aurobindo
9. Fate and Free-Will, Karma and Heredity, etc
Jādu (magic) is a special practice which is done by professional magicians or those who learn the art of the magician, but it is no part of yoga. What happens in yoga is that sometimes or even very commonly certain powers develop in the sadhak by which he can influence others or make them do things or make things happen that he wants. This and other yogic powers should never be used by the sadhak for egoistic purposes or to satisfy his vital desires. They can only be used when they become part of the realised divine consciousness by the Mother herself or at her command for good and unselfish purposes. There is no harm in yogic powers that come naturally as a part of the new consciousness and are not used for a wrong personal purpose. For instance you see something in vision or dream and that happens afterwards in the waking state. Well, that is a yogic power of prevision, knowing future things which often occurs as the consciousness grows; there is nothing wrong in its happening; it is part of the growth in sadhana. So with other powers. Only one must not get proud or boast or misuse the powers for the sake of desire, pride, power or the satisfaction of the ego.
The vision you saw of the man and the fire at his feet was probably a vision of the God Agni from whom flows the fire of tapasya and purification in the sadhana.
When the sadhana progresses, one almost always gets the power of vision; what one sees is true if one remains in the right consciousness. There are also wrong voices and experiences. The people who have gone mad, went mad because they were 
egoistic, began to think themselves great sadhaks and attach an exaggerated importance to themselves and their experiences; this made them get a wrong consciousness and wrong voices and visions and inspirations. They attached so much importance to them that they refused to listen to the Mother and finally became hostile to her because she told them they were in error and checked their delusions. Your visions and experiences are very true and good and I have explained to you what they signify – the wrong ones tried to come but you threw them away, because you were not attached to them and are fixed on the true aim of sadhana. One must not get attached to these things, but observe them simply and go on; then they become a help and cannot be a danger.