> Yes, I have just started. I got home from work a few minutes ago, and
> poured a stiff martinis to consider Les and John's great
> answers. Thanks to both of you. It is difficult to get good answers
> from very vague and confused questions, and I appreciate the effort.
> I thought Les's comment on the religious features of the Lagrangian
> was hilarious.
Since I'm late to the party, I won't add any more discussion of the math. But philosophically I've always thought of a principle of stationary ("least") action as saying that a system will only move to configurations which don't require it to create or destroy energy by mechanisms not specified in the problem's inputs.
I agree that the idea of "least" action is quasi-religious. I would say that "stationary" action is much less religious in character, because it says that energy has to come from or go to somewhere physical -- there's no Noodly Appendage out there jostling physical systems around just for kicks.