"In 1927, the year that Heisenberg announced his "uncertainty principle," Niels Bohr also described the 'principle of complementarity' for quantum systems: for every measurable quantity there exists a 'complementary' measurable quantity. The more accurately one measures one, the more impossible it becomes to simultaneously measure the other.
"Born told us that at the end of Bohr's magnificent lecture, someone in the audience asked him, 'What, then, is complementary to truth?'
"Born said his colleague replied, without any hesitation, 'Clarity.'"
-Max Born
1882-1970
