Because a given era lacked a given body of information, we...

Because a given era lacked a given body of information, we feel that its whole consciousness was naive. We can, therefore, sniff at, say, twelfth-century imagery of evil along with twelfth-century notions as to the shape of the solar system. The idea is that, having come upon information that supervenes the medieval cosmology, we can thereby dismiss all medieval notions as merely medieval.