Einstein believed that physics was about trying to figure out how the real world actually works. Bohr believed, especially after all the weirdness of quantum mechanics was seen, that all physics could hope to do was come up with mathematical models that might have nothing to say about what was really out there in the real world.
I think it's interesting that this article is about important equations that have had such a great effect on civilization and yet we don't know if they are really telling us anything about what's out there beyond our limited, error-prone, and failing senses.