ABSTRACT
As science gives us ever more surprising knowledge we become less certain of what we know, and perception becomes even odder. The notion that we are born with certain knowledge, and that perception reveals truth, has been eroded over the centuries so now we may well ask, 'What is illusion - what true?' Science does not claim more than hypotheses to describe and explain the seen and unseen world. Much of science saves the appearances by suggesting hypothetical models for restructuring our perceptions. Milton puts this beautifully for astronomy at the time of Copernicus, in Paradise Lost (Bk vii, I, 23):
He his fabric of the Heavens Hath left to their disputes, perhaps to move His laughter at their quaint opinions wide Hereafter, when they come to model Heaven And calculate the stars, how they will yield
The mighty frame, how build, unbuild, contrive To save appearances, how gird the sphere With centric and eccentric scribbled o'er, Cycle and epicycle, orb in orb.
