( Story told by Swami Vivekananda )
Once in Western India I was travelling in the desert country on the coast of the Indian Ocean. For days and days I used to travel on foot through the desert, but it was to my surprise that I saw every day beautiful lakes, with trees all around them, and the shadows of the trees upside down and vibrating there. ‘How wonderful it looks and they call this a desert country!’ I said to myself. Nearly a month I travelled, seeing these wonderful lakes and trees and plants.
One day I was very thirsty and wanted to have a drink of water, so I started to go to one of these clear, beautiful lakes, and as I approached, it vanished. And with a flash it came to my brain, ‘This is the mirage about which I have read all my life,’ and with that came also the idea that throughout the whole of this month, every day, I had been seeing the mirage and did not know it.
The next morning I began my march. There was again the lake, but with it came also the idea that it was the mirage and not a true lake. So is it with this universe. We are all travelling in this mirage of the world day after day, month after month, year after year, not knowing that it is a mirage. One day it will break up, but it will come back again; the body has to remain under the power of past Karma, and so the mirage will come back. This world will come back upon us so long as we are bound by Karma: men, women, animals, plants, our attachments and duties, all will come back to us, but not with the same power. Under the influence of the new knowledge the strength of Karma will be broken, its poison will be lost. It becomes transformed, for along with it there comes the idea that we know it now, that the sharp distinction between the reality and the mirage has been known. (CW, 2:281-82)
Source: The Complete Works of Swami Vivekananda/Volume 2/Jnana-Yoga/The Real and the Apparent Man