 Descartes was part of a tradition that denied action at a distance. This orthodoxy included Galileo. He was distressed by Johannes Kepler’s hypothesis that the moon influences the tides because the hypothesis seems to require causal chains in empty space. How could the great Kepler believe something so silly? After Isaac Newton resurrected Kepler’s hypothesis he eventually capitulated to orthodoxy and stuffed the space between the moon and the Earth with ether.