When I learned about meditation as a teenager, I gave it a try.

It was nice, a good way to relax.

Then one day I wondered, could I visualize a lit red candle so vividly that my brain responded as if I were actually seeing it? Not in the amorphous form of imagination but as if the nerves in my eyes were transmitting the image of the candle to my brain.

And I found that I could. Its terrifying at first, but you get used to it.

Then I wondered, if I can meditate so hard that if I can make my eyes see something that is not there, can I meditate so hard that I can make my ears hear things that are not there?

And I can.

And it is far more terrifying. Do not recommend.

It's much harder to control.

The last thing you want when you are alone in your room, deep in meditation and your whole body is humming with the fundamental note of the universe trying to summon a phantom orchestra is to hear someone say things.

That will straight up make you think you are crazy.

Just to be clear, I did check, I don't see things or hear things when I am not trying to make myself see or hear them, and otherwise I am sane enough to operate in modern society.

>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.

Yeah that's why firekisina is not recommended by most Buddhist Vipassana meditation paractioners. Without a mentor who understands it nearby it has side effects that can make one go crazy.

Thanks, fixed.