Max has multiple personalities.  He's either very, very good or very, very bad.  I really do think he
has a split personality.  One moment, he's very sensitive to the leg, and the next minute, he's not.
In his stall, he's the biggest slob in the world.  We have to pay stall muckers extra just to go in
there.  He also scatters his hay around and overturns his water buckets at every chance.
Amazingly, this slob has good ground manners.  He's one of the more advanced, highly trained
horses in the barn, and he's usually kind to riders, when he's in the mood.
The Corridor of Aids
The language for training is much more detailed than the language for riding.  Training requires a
"corridor of aids."  Think of this corridor as having flexible walls and a door at the front and back.

You control the front wall with your hands.  To move the whole
wall forward, you push with both hands.  If you push with just one
hand, the corresponding side of the front wall swings forward.  If
you pull back with both hands, the wall comes toward you.

You control the back wall by working your seat in conjunction
with your legs.  If you close both legs, the back wall moves
forward.  If you press in with one leg, the corresponding side
of the back wall moves forward.  If you cease using both legs,
the back wall falls away.

You control each side wall through the legs, seat, and hands on
that particular side.  For example, if you close your right hand,
press in with your right leg, and put weight on your right seat
bone, the right wall moves in.

Example: Moving to the Left
Play with this corridor a little bit by asking Max to move directly to the left (a full pass).  What do you

1.  Close the front wall, because you don't want him to move

2.  Close the back wall, too, because you don't want him moving

3.  Make the whole righthand side active, and open (make
passive) the whole lefthand side.

What does this mean?  Sit on your right seat bone, close your right leg at the girth, and hold the
horse's head and neck straight with your hands.  That will cause the right wall to move left.  In other
words, the horse will take a step to the left.  Yes, this is a leg yield.
Of course, many things can go wrong.  Max might walk or drift forward, back up, bend to the left or
right, or just stand there.  But with subtle and continuous adjustments of the corridor of aids, plus
reinforcement, you'll accomplish this movement.

Horse in a Box Frame
To use another analogy, when training horses think of each as being in an old-fashioned box frame.  
The frames come in all sizes and shapes.  The frame a particular horse travels in is determined by the
parameters you set through your legs, back, and hands.  You never allow the horse to venture
outside this frame.  Horses that attempt to do so must be corrected.

Example: Moving Forward, Long and Low
Now try a longitudinal move.  You want Max to move forward, long and low.

1.  Push the front wall forward.

2.  Close the back wall.

3.  Keep both side walls in close so the horse stays straight.

Example: Marching Forward
Suppose you now want Max to march, that is, move with a more elevated step.

1.  Close the front wall.  Set is by pushing down your thumbs,
but lift your hands to make sure it doesn't collapse.

2.  Force the back wall up underneath the horse's hindquarters.
Move both legs behind the girth with a slapping motion, and
take a very deep, driving seat.

Max is jumping up and down inside the corridor.  Make sense?  Good!  You're now a trainer.  You
know how and when to use your corridor of aids.

What to do if...your horse evades by shifting his hindquarters to the left and traveling
Close the left hind quadrant of the left wall.  Bring your left leg back, behind the girth, position your
right leg at the girth as a guard, and push the hindquarters to the right, back into the corridor.  You're
now traveling straight and forward.
Woodland Horse Center