Adi Shankara (died 820 AD) was a philosopher and theologian from India who consolidated the doctrine of Advaita Vedanta. He is credited with unifying and establishing the main currents of thought in Hinduism. One of the key philosophies which he taught was of ‘māyā‘ (illusion).
It was a fundamental concept in Hindu philosophy, notably in the Advaita (Nondualist) school of Vedanta. Māyā originally denoted the magic power with which a god can make human beings believe in what turns out to be an illusion. By extension, it later came to mean the powerful force that creates the cosmic illusion that the phenomenal world is real.
Shankara says everything is illusory. Whatsoever you are seeing, hearing, feeling, all is illusion. Nothing is real because the real cannot be contacted by senses. You are hearing me and I am seeing you hearing me: it may be just a dream, and there is no way how to judge whether it is a dream or not. I may be just dreaming that you are here listening to me. How am I to know that this is real and not a dream? There is no way.
Shankara says with senses there is no possibility to know whether the thing confronting you is real or unreal. And if there is no possibility to know whether it is real or unreal, Shankara calls it Māyā.
For the Nondualists, māyā is thus that cosmic force that presents the infinite brahman (the supreme being) as the finite phenomenal world. Māyā is reflected on the individual level by human ignorance (ajnana / agyān) of the real nature of the self, which is mistaken for the empirical ego but which is in reality identical with brahman.
One day Adi Shankara was giving a sermon and expounding his philosophy. One of his opponents was standing nearby listening. As soon as Shankara started talking about ‘māyā’, the man shouted at the top of his voice: “Run, a wild bull is charging!”
On hearing this the assembled panic stricken crowd started running. In the melee Adi Shankar too could be seen running to save himself. On seeing him run, the man laughed and again called out: “Shankara! Why are you running if everything is māyā? Why are you afraid of an illusionary bull?”
Shankara stopped running and quietly replied: “My running was also a māyā – illusion.”
The man was speechless. Adi Shankara had outwitted him!