Why Chinese meditation masters (Buddhism and Taoism) tell you to touch tongue to roof and teeth don't touch

 I figured this out recently.

There's two things they tell you to do with your mouth area.

1. touch the tongue to the roof of your mouth during meditation

2. upper teeth and lower teeth don't touch, jaws are not clenched shut.

#1 becomes pretty obvious even after just a couple years of serious meditation.

When you touch the tongue to the roof of the mouth, you get a solid, energetic connection. 

At times, it can like you just touched your tongue to a nine volt battery and get an electric shock when the tongue connects to roof. 

Or just mild tingling vibrations.

It all depends on how saturated your jhāna battery is. 

If you have a big battery (from many years of dedicated meditation) and you're very charged up at the time, it won't feel much difference between touching the roof with your tongue or not.

It's like a free way with 10 lanes, if you open up an extra lane (touching tongue to roof), it won't affect the flow of traffic much.

But for a beginner meditator, whose energy channels are completely blocked, or clogged with lots of energetic gunk, their freeway only has one lane, and if you open up a second lane suddenly traffic flow can increase greatly.

#2 puzzled me for a long time. Why isn't it ok to touch the upper and lower teeth?

I just ignored those instructions all these years, since I never had any (negative) issues or could tell the difference if my upper and lower teeth were touching each other or not.

But recently I figured out why the masters gave that instruction.

It's because most meditators, will feel big energetic blockages in the chest, head, mouth areas.

And when you meditate with sufficient passaddhi (pacification/ relaxation), jhānic force will start clearing out blockages in the jhāna highway. 

You feel that as vibrations, force, feelings of tightness, compression, expansion, for many people discomfort and various degrees of pain.

Some (or maybe many) meditators will unconsciously clench their teeth in response to jhānic force trying to clear out the jhāna highway (loops of energy running through the body).

I've even read about some meditators who've had teeth fall out, from the forces experienced on their mouth and teeth.

I personally never had issues with unconsciously clenching my teeth, but I've definitely had stages where I feel strong forces pushing on the teeth from the roots, as if the teeth wanted to come out.

In conclusion, a better instruction from the Chinese meditation masters for #2, would be this:

Keep your mouth relaxed, tongue relaxed, teeth relaxed.

If you feel involuntary clenching of teeth, try not to close your jaw all the way, keep a little space so the teeth aren't touching.

If you don't have any tension in your mouth, teeth are completely relaxed, then touching upper and lower teeth and having jaw completely closed is not a problem.

So the error they made was not clearly explaining why they have that rule.

It all comes to the 7 awakening factors, especially the one on passaddhi (pacification/ relaxation).

Most meditators will feel pain in various parts of the body as jhānic force surges and tries to clear out and dissolve problems in the body. 

And most people will consciously and unconsciously respond to pain and discomfort by tensing up various parts of the body.

Even if they feel back pain, clenching their teeth or furrowing their brows and making angry faces doesn't help.

Tensing up those parts just blocks and hinders the passaddhi awakening factor, and slows the work of jhānic force healing your body.

I know it's hard, but you have to try to stay relaxed in every part of the body even when it hurts, if you want to progress the fastest way possible.

If pain becomes too hard to tolerate, doing accupressure, yoga, stretching, walking, dynamic stretching exercises, taiji and qigong type of exercises will help dissolve blockages faster than just sitting or standing in static meditation postures.

This is why step 3 of breath meditation (16🌬️😤‍ ) is so important to translate and interpret correctly.

You can't relax what you don't even realize is tense and not relaxed.

So learning to be sensitive to the entire physical body, every cell, every tooth, every body part, is how you discover where you're tense and blocking and hindering kāya-passaddhi (pacification) awakening factor. 

If you can feel/sense it, you can learn to relax it, whether it's teeth clenching, mouth tensing, etc.

And when you can feel the jhānic force dissolve tension and blockages, then you learn how to relax even more, both body and mind, to amp up the force and current flow.