C.S. Lewis held the conviction that all humans have meaningful images embedded in their minds that are often expressed in myths and legends. The richness of the Narnia Chronicles is often traceable to mythic patterns and philosophic thought employed by Lewis.
In The Chronicles of Narnia, C.S. Lewis envisions heaven through the symbolic presentation of “Aslan’s Country.” Every other world is linked to it as a peninsula is connected to a mighty continent. It can be reached only through magic or more often “the door of noble death.” Its boundaries expand according to the exploration quests of its inhabitants. Hence, Aslan’s admonition to come “further up and further in!”
Fisher, H. Dennis
"C.S. Lewis, Platonism, and Aslan's Country: Symbols of Heaven in The Chronicles of Narnia,"
Inklings Forever: Published Colloquium Proceedings 1997-2016: Vol. 7
, Article 5.
Available at: https://pillars.taylor.edu/inklings_forever/vol7/iss1/5