Authors:

Revenge is profitable, gratitude is expensive.

Edward Gibbon (2016). “THE HISTORY OF THE DECLINE AND FALL OF THE ROMAN EMPIRE (All 6 Volumes): From the Height of the Roman Empire, the Age of Trajan and the Antonines - to the Fall of Byzantium; Including a Review of the Crusades, and the State of Rome during the Middle Ages”, p.374, e-artnow
Revenge is profitable, gratitude is expensive.