Illusion means that the content of our experience blinds us to its context
Sometimes we get so caught up in watching a movie that we forget where we are, even who we are. The content of our experience, the hopes and horrors of the movie characters, make us oblivious to the context of that experience: the reality that we are observers seated on a chair, distinct from the happenings in the movie.
When the content of an experience blinds us to its context, that blinding effect is the essence of illusion. Similar is the illusion that traps us souls in material existence. We get so caught up in the pleasures and pains of the body that we forget who we are – the experience makes us oblivious to the experiencer, the source of consciousness, the soul.
The difference between a movie and material existence is that in the latter we are not just spectators but also actors. Tragically however, as actors we are not victors but victims. The actions we do to gain pleasure and avoid pain bring karmic consequences that incriminate us further in material existence, thereby subjecting us to greater illusions.
To come out of this illusion, we need philosophical education and personal introspection. The Bhagavad-gita (06.18) indicates that those who bring their consciousness under control by rejecting sensual desires become situated on the spiritual platform, free from illusion.
Intriguingly, not all illusion is bad. In the highest level of existence in the spiritual world, Goloka Vrindavana, devotees relish such exciting and fulfilling experiences in loving Krishna that the content makes them forget the context; they become oblivious to the supreme position of Krishna and their subordinate position. They delight simply in the reciprocation of love. That divine illusion is existence’s supreme achievement – the perfection of pure and perennial love.
"When the yogi, by practice of yoga, disciplines his mental activities and becomes situated in transcendence – devoid of all material desires – he is said to be well established in yoga."