Great minds, like heaven, are pleased in doing good, Though the ungrateful subjects of their favors Are barren in return. Nicholas Rowe (1674-1718) English poet and dramatist Tamerlane, Act 2, sc. 2 (1701)
Men are more ready to repay an injury than a benefit because gratitude is a burden and revenge a pleasure. Tacitus (c.56-c.120) Roman historian, orator, politician [Publius or Gaius Cornelius Tacitus] (Attributed) In Machiavelli, The Discourses, 1.29 (1517) [tr. Detmold (1940)]