Thanks. I don't know about common knowledge. I was trying to see what others had to say about it.
Gleason sensei talks about the palm being earth. He shows hand of fire and hand of water, etc. It is crystal clear when he shows it. I copy him and it all makes sense. 10 minutes after I walk out of class I think - which hand orientation was "fire"? I assume I have a mental block about it. I was hoping a few other perspectives would help me over my mental barrier(s).
If I remember correctly from a Gleason seminar, fire hand is palm up and ascending away from the body and water hand is palm down descending into the body - or water hand is aiki and fire hand is kiai,,, (energy in and energy out)