Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
As quoted in The Cyclopedia of Practical Quotations (1896) by Jehiel K̀eeler Hoyt, p. 763
Édouard Fournier, in L'Espirit dans l'Historie (1867), 3rd edition, Ch. 51, p. 260, disputes the traditional attribution, and suggests various agents of Richelieu might have been the actual author.
David Hackett Fischer, in Champlain's Dream (2009), Simon & Schuster, p. 704, n. 14, says it's a paraphrase of Quintilian and there is no source closer to Richelieu than Francoise Bertaut's Memoires pour servir à l'histoire d'Anne d'Autriche.
Disputed
Armand Jean du Plessis de Richelieu: Idézetek angolul
As quoted in The Catholic Encyclopedia (1913), edited by Charles George Herbermann
As quoted in Champlain's Dream (2008) by David Hackett Fischer
“We may employ artifice to deceive a rival, anything against our enemies.”
Pour tromper un rival l'artifice est permis; on peut tout employer contres ses ennemis.
As quoted in Dictionary of Quotations from Ancient and Modern English and Foreign Sources (1899) by James Wood
Variant translation: To mislead a rival, deception is permissible; one may use all means against his enemies.
“Deception is the knowledge of kings.”
Savoir dissimuler est le savoir des rois.
“Maxims,” Testament Politique (1641)
“The last reasoning of Kings.”
Ultima ratio Regum
A comment upon artillery fire, as quoted in Dictionary of Foreign Phrases and Classical Quotations (1908) edited by Hugh Percy Jones, p. 119; these words were later inscribed upon cannon of Louis XVI of France.