I was training in Hombu dojo one day in Noda and both my training partner and I were scratching our heads over something Oguri Sensei had just demonstrated.
We would see him move and the result he had on the uke. Then we would try. And the results were not as wonderful. I looked down at Oguri's feet and noticed their position. Something clicked in my head. I asked my training partner to attack again. It worked!
What I had noticed was Juuji. Or, rather, the perpendicular angle of Oguri to his uke's kamae. Often this angle is called Juuji because of the kanji and how it suggests this right angle. This angle can be extremely powerful.
In this instance it was deceptive and hard to notice at first. Usually this Juuji idea is obvious when you have the Uke in kamae going one way, and the Tori is going crossways with his kamae. In this case Oguri had a subtle kamae, and the perpendicular angle was crossing out at the end of the attack where it achieved maximum leverage.
At that moment in class, I couldn't understand. I was just miming Oguri Sensei's positioning. My partner and I shared this exchange:
Me: "It seems to work better from this position."
He: "Yes... But, Why?!"
Me: "I don't know."
All I could do was absorb more of Oguri's teaching to save it for later. That is often how it goes. I may not understand it on the spot, but some months or years later I have that "Aha!" moment.
Update 1/17/2012 :