Just a couple interesting observations (to me at least)
First is that although the books mentioned minimized the DR connection, at least the Spirit of Aikido (pre-Tohei split) has a lot of detail about ki and the books published after the split do not.
The other observation is that it appears the lesson is to 'live and let live' and to allow things to flow naturally - can it all really be that simple? - IMO, why not; some of the most complex things have a very simple foundation, so why not Budo and Aiki. I also like the use of 'joining' and 'reconciliation' as the union of opposites, sounds a lot like in/yo and yin/yang to me; which plays a big
role in the development of the Aiki body