In the late fifteen-century, the earth stood motionless at the centre of a small, ordered cosmos. Around us, it was believed, the moon, the sun and the planets revolved in crystalline spheres, their orbits perfect, eternally unchanging circles. Just over a century later, the sun was now the centre of creation; the earth just another planet hurtling through empty, near-infinite space. This is the story of an astonishing change, a transformation in human thought, about both the universe and our place within it, told through the words of the astronomers and mathematicians at its heart.