"There are five principal elements present in the universe - get that look off your face, it's not as absurd as it sounds. The masters of old used to believe that all things were made of fire, water, air, earth, and metal. Obviously, modern science has proven that false. Still, it's a useful mnemonic for understanding the different types of energy.
 

"Fire: the heat in your blood in the midst of a fight, the kinetic energy that makes your heart beat faster. Jiang tapped his chest. "Water: the flowing of force from your muscles to your target, from the earth up through your waist, into your arms. Air: the breath you draw that keeps you alive. Earth: how you stay rooted to the ground, how you derive energy from the way you position yourself against the floor. And metal, for the weapons you wield. A good martial artist will possess all five of these in balance. If you can control each of these with equal skill, you will be unstoppable."

 

 I felt that I had finally realized my dream, that I had become exactly the sort of man I wanted, a man of means and power, a man whose contracts were recorded by flattering notaries. But as time went on, I fell for the magic of numbers and the allure of profit. I was preoccupied only with the price of things and neglected to consider their value. So long as I managed to sell at a higher price, it no longer mattered to me what it was I sold, whether glass or grain, wax or weapons, or even, I am ashamed to say, especially in consideration of my later fate - slaves.

 

- Laila Lalami, The Moor's Account.