The universe would look to a two-dimensional creature who spend its life moving on the service of what turned out to be a globe, it could travel for millions of years and would always return to its starting point, it would never be conscious of what was above it or beneath it.
The Liskov Substitution Principle is a fundamental concept in object-oriented programming, stating that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program.