As far as who taught what, I'll defer to the historians and scholars who are doing great work in unearthing details of the early years of Reiki.
In my own experience, people take on ownership of the self-healing principle much more readily if they have to give in order to receive.
Lots of judgment and flexibility needed in implementing the policy of exchange, but a must-do if you're going to practice on others much at all. If you always give it away, you'll reach a point of exhaustion and resentment.
Exchange enables balance.
Blessings,
Aronaya
