The “I” is the root of one’s negativity. It is imaginary.

In math, the imaginary unit is defined as the square root of negative one:

\[ i = \sqrt{-1} \]

For some motivation, consider what values for x satisfy the following equation

\[  x^2  = 1 \]

Both +1 and -1 work.

Instead, try to think of values for x that satisfy this equation

\[  x^2  = -1 \]

No real number does! Squaring both positive and negative numbers always gives another positive number.

If we allow for the existence of some number with the property that squaring it gives -1, then a solution to the equation would be found. This is precisely what the imaginary unit is constructed to do, and is equivelent to the definition given above since

\( i^2 = -1 \) implies \( i = \sqrt{-1} \).

Adding this imaginary unit together with any real multiples of it to the usual set of real numbers gives you the complex numbers. This is a number system so rich in its structure that much of modern mathematics and science is dependent on its existence. For instance, the theory of quantum mechanics makes heavy use of imaginary numbers, many fractals are constructed using them, and even the pretty colors plotted on this site are exploiting them.

And they would say you couldn’t take the square root of negative numbers!