One scientist proposes, theorizes something today and another scientist makes this proposition, this theory, null and void and he speaks something else. That is also due to the imperfect of senses. So that is called mistake or illusion. Mistake means calculation, mathematical calculation. Two plus two equal to four, but sometimes by mistake we may put three or five. That is called mistake. And illusion, to accept something for something. Just like we are accepting. When somebody inquires, "who are you?" You just give identification of your body: "I am such and such, I am an American, I am born of such father and mother." But this body is not yourself, you are spirit soul. Therefore, it is called illusion. And because we are standing on the platform of illusion, there is mistake, there is cheating, and the senses are imperfect. This is the position.
Letter to Yadubara, 13 September, 1972