Why do you add milk to breakfast cereal?

How was breakfast cereal invented? What magical ingredient made cereal so popular? What is the most popular cereal of all time? For free home activities sign-up at www.WhoSmarted.com See omnystudio.com/listener for privacy information. See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.