Explanation:
Rare property of obsidian that is advantageous to archaeologists is that it occurs in volcanic flows that are remarkably homogeneous in chemical composition within a flow, but preserve elemental signatures that are unique to volcanic centers, and in some cases individual flows.
The philosophers during the middle ages believed that the geocentric model of the Universe was the one that is true. This model presupposed the Earth being the centre of the universe and the Sun revolving around the Earth - this, of course, isn't true.
It taught them structure in their lifes
