Question

why is the rule of law considered the foundation of any country

Answer 1

A principle that itself is quite old and long predates the United States, the rule of law is the general concept that government as well as the governed are subject to the law and that all are to be equally protected by the law. Its roots can be found in classical antiquity.

Just like man cannot exist without plants (which acts as one of our sources of food and oxygen) and vice versa (plants needs our CO2), such is the relationship between rule of law and democracy.

Democracy is a system through which the people exercise power through their elected representatives. And in order for this system to be smoothly run, fair and void of tyranny, there is need for a concept that entrenches equality. Which is one of the features of the democracy.