Sometimes, it also happens that, the surface of water has oil in it – or some other liquid. In this case too, the reflection/image and the illumination is not perfect. This is what happens with you and me. So to get a perfect image, you need knowledge. Now you can’t do it yourself, because you’re the water mixed with oil. Someone else has to do it for you. This person is called – “Guru” or “mentor” who cleanses you, you takes the oil out of the water.