1EJ,
I think Feynman meant the unintuitive nature of Quantum Physics and the math works, so shut up and calculate. That is my understanding of the phrase.
When we scale down to sub atomic particles we find our intuitions for our middle macro scale don't apply.
O and I don't consider Deepak a mystic only some one who may repeat something that the mystics have said.
https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#shutup