Here's a quote:
It got me thinking about the how way we move our head affects our aikido. Balancing on top of the spine and held in place by a complex system of muscles and ligaments, the head has a centre of gravity all its own. When attempting to break uke’s balance (kuzushi) ultimately we are trying to pull the spine out of alignment by destroying the head’s centre of gravity. And at the same time we are trying to maintain the stability of our own head and upright structure.
It reminded me once again that there are two people in any technique, and my first thought should be about my own stability, before I start trying to interfere with anyone else’s.