E, perché sono di tre generazione cervelli, l'uno intende da sé, l'altro discerne quello che altri intende, el terzo non intende né sé né altri, quel primo è eccellentissimo, el secondo eccellente, el terzo inutile, conveniva per tanto di necessità, che, se Pandolfo non era nel primo grado, che fussi nel secondo: perché, ogni volta che uno ha iudicio di conoscere el bene o il male che uno fa e dice, ancora che da sénon abbia invenzione, conosce l'opere triste e le bunone del ministro, e quelle esalta, e l'altre corregge; et il ministro non può sperare di ingannarlo, e mantiensi buono.
Because minds are of three types; the first understands by itself, the second understands what others explain, and the third understands neither by itself nor by the help of others; of which the first is excellent, the second very good, and the third useless. So it follows that even if [Prince] Pandolfo was not in the first class, he must necessarily have been in the second: because such a prince has the judgement to know the good and evil that another says and does, even if he himself lacks the initiative, and he sees the good and bad works of his minister, exalting the good and correcting the bad; and the minister cannot hope to deceive him, and so behaves well.
IL PRINCIPE The Prince, XXII DE HIS QUOS A SECRETIS PRINCIPES HABENT Concerning Princes' Ministers — Niccolò Machiavelli, 1513
In The Prince, Machiavelli was attempting something that had not been done since the Classical period. He considered history not as divine plan, but as an explicable sequence of events. There was chance, and there was human response to it; and the humans were motivated by the usual earthly things. And then he considered what we might learn. It's a book people have heard of - a book people still talk about, 496 years on. Because, while the events and the people he mentions are very far away, it is extremely clear that he saw the world as we do.
When I was about 18 I went and got the Penguin Wordsworth translation (the above is not that translation, but my own from my Italian edition, so errors are mine) and read it to find out what it said. I'd entirely recommend this. It's rather short. A lot of what he says feels applicable and plausible. With more years, I may more often think he's wrong, but I still think he's elegantly, interestingly wrong.
I don't think I agree, for example, that there are three kinds of mind. Or, if there are, each of us has all three, perhaps in different fields. But it's a very plausible notion, and anyone could think of examples. If I look for examples of the third kind of mind, though, I tend to find examples of lack of motivation. I don't think people very often understand something without wanting to, even if they are more than capable of understanding more complex things they do want to understand. I certainly don't think anyone gets good at something without wanting to, unless they're an autistic savant, and it seem unlikely even then.
But what really comes to mind when I read that passage again in isolation, is not the relationship of head of state and minister, but the parallel relationship of student and teacher.
Good and bad outcomes have a lot to do with teachers. But they have everything to do with the judgement and motivation of the student.