I know the main purpose of this essay is not to discuss where Lucas got his inspiration but I just quickly want to add in regards to addendum#1 that the force is also similar to the concept of qi.
Discuss away. A lot of this essay and the responses have gone into Lucas’ inspirations, so it is in no way off-topic.
As for qi, I only know a little bit about it, mostly just the cliches, but it does seem like the kind of thing that Lucas might have referenced, especially since all things new age and martial arts related were quite big in the 70’s.