Hippocrates believed that there are four humors in human body which need balance for a healthy being. These were:
Blood, phlegm, yellow bile, and black bile.
Galen expanded the idea of the humors and introduced four temperaments which were these:
choleric (hot / dry), melancholic (cold / dry), sanguine (warm / moist), and phlegmatic (cold / moist).
Another expansion Galen did was that he gave each humor/temperament physical and psychological qualities and said that even the food items have an association with the certain humor, those foods can effect certain humor in certain ways.
