>Then I wondered, if I can meditate so hard that if I can make my eyes see something that is not there Those are called Nimitta (sign) and if your samadhi is s

>Then I wondered, if I can meditate so hard that if I can make my eyes see something that is not there Those are called Nimitta (sign) and if your samadhi is stable enough you can focus on those signs and start manipulating them. Here is how: Focus your mind upon it and then try to change color, turn it into nearest color of the sign you are seeing. For example if it is yellow, try to make it paler or whitter, redder, etc. If it is successful and you can turn to any color as you will, try to make it bigger and bigger, or then make it smaller, and turn into nearest shape. If it is circle turn it into oval, to square, etc. then zoom it into more and more till it cover whole visual scape. There you will start experiencing the effects of jhana and otherworldly experience that can only be described by the experiencer.