In the Divine Comedy Dante describes travellers journeying through the Earth. He and his fellow travellers go down to the centre and continue and immediately realise that they are going "up". This indicates that gravity was understood to be a force or attraction coming from the centre on the Earth rather than, as we now know, a force coming from every part of the mass of the Earth (though in practical terms this difference in understanding only makes a practical difference if you are inside the Earth - outside the Earth the force under the two understandings would behave the same). What else did people in the Middle Ages know about gravity? Did they, for example, know that the same force which was responsible for pulling objects on the surface of the Earth down was also responsible for keeping the Moon in orbit? Note: At the risk of stating the obvious, Dante did not actually travel inside the Earth: he was writing fiction, albeit fiction which sheds light on contemporary beliefs about the Earth and its gravity.