The insight which led Heisenberg in 1925 to the formulation of quantum mechanics was in some respects as momentous as the Copernican insight into the ordering of the heavenly bodies; for it changed the point of perspective from which physicists since the time of Copernicus were accustomed to look at the world. It changed a viewpoint about the world which had become classical and tumbled down a pile of certainties on which the physics of three hundred years had been based. Heisenberg called these the "ontology of materialism", that is, the certainty that nature was out there, solid and material, infinitely accessible to objective description, in which the goal of each succeeding generation of scientists was the conquering of yet another decimal place². Quantum mechanics showed that this goal was a mirage; it revealed the presence of a subtle subjectivity at the very heart of the scientific enterprise, and, by so robbing the mind of its solid support, left it as Heisenberg said, 'suspended as over an unfathomable abyss' — the unfathomable and mysterious abyss of its own subjectivity³. Even in the moment of its conception, Heisenberg, Bohr and the small circle of intimates who surrounded them, knew that the structure of quantum mechanics was of critical importance for more than scientific method. They realized that it destroyed one ontology of nature and profoundly affected the science of the intimate structure of the human mind.