Imaginary Numbers: An Absurd Starting Point or a Mathematical Necessity?

Abstract

If a negative number multiplied by itself equals a positive number, then it�s hard to understand the square root of a negative number. [1]

I read somewhere, but I cannot find the source: �When we teach complex numbers, we usually start with an absurd assumption. We define i to be the square root of -1. Then, we construct this elegant theory. But since we start with an absurd assumption, many people have this lingering doubt. We don't have to start from an absurd point.� Yes, the statement is right I think. What is this absurd point that is the starting point for imaginary numbers and hence for complex numbers?