A cable supporting a horizontal load takes the form of a parabola, as illustrated here on London's Tower Bridge. The natural laws of force that govern this phenomenon are the same laws that govern the motion of planets, or the trajectory of a falling leaf. Isaac Newton invented calculus over 400 years ago to describe such universal principles. Calculus remains a major tool in all branches of science and engineering. The MATH 200–201 sequence is an introduction to this very fundamental, powerful and useful subject.