Visualize the in or Yin breath beginning just below the base of the spine, where, if we had one, our tails would be. Continuing on with the breath in, we picture or visualize Chi rising up our backs. We then find ourselves 'full' of breath at a point around about the back of our heads/neck. We then, gently and relaxed, 'hold full' as we picture the breath/chi coming across our heads until it reaches a point between our eyes. We then gradually breathe out and picture the breath/chi descending. We become 'empty' of breath at a point just below our belly buttons. We then 'hold empty' as we picture the breath/chi going through or under our belly and returning to that point where, if we had one, our tail would be.
Remember this: Breathe in from the bottom of a circle and breathe out off of the top of a circle. Imagine a waterwheel ... driven by breath ... or Chi.

Water cannot flow uphill but , as is the case with canals, it can be raised with the use of locks and lock gates. Similarly, to raise the Chi up our backs, to the rear, across the top and then to the front of our heads we open and then close "The Three Gates".

As we breathe in (picturing the breath/chi rising up our backs) we:
1. Push the ends of our toes into the ground/floor, just like most of us do when we stand in wet sand at the seashore.
2. We 'pull' or 'squeeze up' our pelvic floor, just like most of us do when we are 'caught short' and have to 'hold it in' for a while!
3. We squeeze our tongues against the roof or our mouths.

The Three Gates encourage the flow of Chi to the top of our heads and should all be operated simultaneously on the in breath.

On the out breath we relax or soften the three i.e. the toes, the tongue and the pelvic floor.