"Letters to Atticus" (1st century B.C.), as quoted in "Words on war: military quotations from ancient times to the present", book by Jay M. Shafritz, 1990.
Marcus Tullius Cicero (1853). “The treatises of M.T. Cicero on the nature of the gods [tr. by T.Francklin]; on divination; on fate; on the republic; on the laws; and on standing for the consulship, tr. chiefly by the ed. C.D.Yonge [and F.Barham].”, p.420