“The first ladies ought to be ambassadors as well.”

"Instructions given by Niccolo Machiavelli to Rafael Girolami, Ambassador to the Emperor," The History of Florence and of the Affairs of Italy: From the Earliest Times to the Death of Lorenzo the Magnificent; Together with The Prince, and Various Historical Tracts, H.G. Bohn, Editor, p.505–06 (1854).
Context: Now, in order to execute a political commission well, it is necessary to know the character of the prince and those who sway his counsels;... but it is above all things necessary to make himself esteemed, which he will do if he so regulates his actions and conversation that he shall be thought a man of honour, liberal, and sincere. The latter point is highly essential, though too much neglected, as I have seen more than one so lose themselves in the opinion of princes by their duplicity, that they have been unable to conduct a negotiation of the most trifling importance. It is undoubtedly necessary for the ambassador occasionally to mask his game; but it should be done so as not to awaken suspicion and he ought also to be prepared with an answer in case of discovery.

2016, Presidential transition of Donald Trump (November 2016)

Instructions to the singers in his opera Pelléas et Mélisande, as quoted in 100 Great Operas and Their Stories (1989) by Henry William Simon, p. 371

Source: Cross My Heart and Hope to Spy

Gli ambasciadori sono l'occhio e l'orecchio degli stati.
Storia d' Italia (1537-1540)

Gli Ambasciadori sono gli occhi e gli orecchi de gli stati.
CCLXXVI.
Translation reported in Harbottle's Dictionary of quotations French and Italian (1904), p. 305.
Concetti Politici (1578)

2012 Democratic National Convention

Source: The Importance of Being Earnest

Philippines' Rodrigo Duterte insults US envoy with homophobic slur https://www.theguardian.com/world/2016/aug/10/philippines-leader-calls-us-ambassador-gay-son-of-a-whore-prompting-summons, The Guardian (10 August 2016)