Beyond these personality types of an introvert, extrovert, and ambivert lie the four basic temperaments as observed by the Greek physician Hippocrates (460–370 BCE), often called the father of medicine. Through acute observation, Hippocrates noted temperamental differences in individuals and came up with a theory to explain these differences. He determined there were four basic temperaments and named them choleric, sanguine, melancholy, and phlegmatic. Biochemically based, his theory involved the body “humors” he believed influenced the differences. These humors were blood, black bile, yellow bile, and phlegm. Today, instead of humor, we think in terms of hormones or other biochemical substances that affect human behaviors. The complete content of Hippocrates’…