“ when you see the servant thinking more of his own interests than of yours, and seeking inwardly his own profit in everything, such a man will never make a good servant, nor will you ever be able to trust him ”
 Niccolò Machiavelli, The Prince (1532). copy citation

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“Therefore, it follows necessarily that, if Pandolfo was not in the first rank, he was in the second, for whenever one has judgment to know good and bad when it is said and done, although he himself may not have the initiative, yet he can recognize the good and the bad in his servant, and the one he can praise and the other correct; thus the servant cannot hope to deceive him, and is kept honest.
But to enable a prince to form an opinion of his servant there is one test which never fails; when you see the servant thinking more of his own interests than of yours, and seeking inwardly his own profit in everything, such a man will never make a good servant, nor will you ever be able to trust him; because he who has the state of another in his hands ought never to think of himself, but always of his prince, and never pay any attention to matters in which the prince is not concerned.
On the other hand, to keep his servant honest the prince ought to study him, honouring him, enriching him, doing him kindnesses, sharing with him the honours and cares; and at the same time let him see that he cannot stand alone, so that many honours may not make him desire more, many riches make him wish for more, and that many cares may make him dread chances.” source

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