Re: Relaxing the hips
Aikido philosophy and body movement seems to come almost exclusively from Ueshiba, through his students, whereas tai-chi appears to be a body of knowledge linked to other things e.g. medicine. I have no doubt though, that the Japanese martial arts incorporate the same chinese understanding of posture and that Ueshiba had considered these aspects in aikido (Ueshiba talked about yin and yang in the left and right arm, in movement, and in posture). However it doesn't seem to have been explicitely transferred to aikido instructors. I think understanding these chinese writings can help us to understand aikido, since I believe the principles to be identical.