The word Maya in Sanskrit breaks down to its roots ‘ma’ meaning “to measure or to give form” and ‘ya’ which translates to an article meaning “that”.
Maya when applied to Brahman(the absolute transcendent reality) takes the meaning – ‘that which measures or gives form to the absolute reality’.
In Quantum Theory terms, if Brahman is the Quantum wave, Maya is the collapsing of the wave function when observed or measured.
Because Brahman is the absolute truth, Maya(which we mere mortals perceive) cannot be the truth and hence termed as an illusion.
Maya is the limit of our perception which veils the transcendent truth from us.
Vedanta declares that our real nature is divine: pure, perfect, eternally free. We do not have to become Brahman, we are Brahman. Our true Self, the Atman, is one with Brahman.
But if our real nature is divine, why then are we so appallingly unaware of it?
The answer to this question lies in the concept of maya, or ignorance. Maya is the veil that covers our real nature and the real nature of the world around us. Maya is fundamentally inscrutable: we don’t know why it exists and we don’t know when it began. What we do know is that, like any form of ignorance, maya ceases to exist at the dawn of knowledge, the knowledge of our own divine nature.
Brahman is the real truth of our existence: in Brahman we live, move, and have our being. “All this is indeed Brahman,” the Upanishads—the scriptures that form Vedanta philosophy—declare. The changing world that we see around us can be compared to the moving images on a movie screen: without the unchanging screen in the background, there can be no movie. Similarly, it is the unchanging Brahman—the substratum of existence—in the background of this changing world that gives the world its reality.
Yet for us this reality is conditioned, like a warped mirror, by time, space, and causality—the law of cause and effect. Our vision of reality is further obscured by wrong identification: we identify ourselves with the body, mind, and ego rather than the Atman, the divine Self.
This original misperception creates more ignorance and pain in a domino effect: identifying ourselves with the body and mind, we fear disease, old age and death; identifying ourselves with the ego, we suffer from anger, hatred, and a hundred other miseries. Yet none of this affects our real nature, the Atman.
Maya can be compared to clouds which cover the sun: the sun remains in the sky but a dense cloud cover prevents us from seeing it. When the clouds disperse, we become aware that the sun has been there all the time. Our clouds—maya appearing as egotism, selfishness, hatred, greed, lust, anger, ambition—are pushed away when we meditate upon our real nature, when we engage in unselfish action, and when we consistently act and think in ways that manifest our true nature: that is, through truthfulness, purity, contentment, self-restraint, and forbearance. This mental purification drives away the clouds of maya and allows our divine nature to shine forth.
Shankara, the great philosopher-sage of seventh-century India, used the example of the rope and the snake to illustrate the concept of maya. Walking down a darkened road, a man sees a snake; his heart pounds, his pulse quickens. On closer inspection the “snake” turns out to be a piece of coiled rope. Once the delusion breaks, the snake vanishes forever.
Similarly, walking down the darkened road of ignorance, we see ourselves as mortal creatures, and around us, the universe of name and form, the universe conditioned by time, space, and causation. We become aware of our limitations, bondage, and suffering. On “closer inspection” both the mortal creature as well as the universe turn out to be Brahman. Once the delusion breaks, our mortality as well as the universe disappear forever. We see Brahman existing everywhere and in everything.