" On July 30, 1723, when he was nineteen years old, Edwards wrote in his diary, “I have concluded to endeavor to work myself into duties by searching and tracing back all the real reasons why I do them not, and narrowly searching out all the subtle subterfuges of my thoughts.” A week later he wrote, “Very much convinced of the extraordinary deceitfulness of the heart, and how exceedingly… appetite blinds the mind, and brings it into entire subjection. "

― John Piper , The Supremacy of God in Preaching