Virtual M,
Thanks for the the CS and PCS slingshot explanations. I've done the CS slingshot many times but I'd never done the great phophet (aka PCS) slingshot so I thought that I would give it a try.
I started a noble game as Elizabeth (I'm a Prince level player but figured that I would make it easy for myself during this test game).
I did everything explained: Beelined to COL, left masonry alone etc. I got Stonehenge in London around 1500bc and was building Oracle at my second city by that time. I built a Hindu temple in London and added a priest to get the prophet churned out (no problem with Lizzy's philosophical trait).
I got my great prophet with about 5-10 turns left on Oracle and fully researched Civil Service with him. Just a few more turns and I'd have Nationalism right? I was all going to plan.
But wait a minute Oracle gets built and no Nationalism option.
It seems that Nationalism requires
Civil Service AND (Philosophy OR Divine Right)!
I had to settle for philosophy and a third religion. The only way for me to pull of the Nationalism slingshot (that I can see) would be to get another great prophet to research Divine Right before getting Oracle (this may be possible on low levels).
At the time of building the Oracle Nationalism was a hefty 99 turns of research out of my grasp (Philosophy and Divine Right were 30-40).
So either I'm missing something here or the PCS isn't quite what it was stated to be.