## Footnote

^{2}Lord Kelvin, the mathematical physicist and engineer, once joked that a mathematician is a person for whom this equation is as obvious as the equation 2 + 2 = 4 is to the average person!

^{2}Lord Kelvin, the mathematical physicist and engineer, once joked that a mathematician is a person for whom this equation is as obvious as the equation 2 + 2 = 4 is to the average person!