Isaiah Berlin, Three Turning-Points in Political Thought, Storrs Lectures, Yale, 1962; first lecture published 2002.
From the second, unpublished, lecture, on Machiavelli, in Unpublished Writings at The Isaiah Berlin Virtual Library.
"His concrete recommendations are governed by the strictest moral values which, contrary to received opinion, are not cynical, not detached, not irresponsible in the least. Croce is right in thinking that Machiavelli is none of these things. He desires an Italy free from the barbarians – the famous eloquent last pages of The Prince and every page of the Discourses are written by a man possessed by a most passionate ideal of life, firmly committed, prepared to sacrifice everything to a form of life that he regards as at once attainable and the fulfillment of all that he and, in his opinion, mankind need and believe in."
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See Machiavelli, The Prince, in Great Books of the Western World (first edition, 52 Vol., 1952) volume 23, (second edition, 60 Vol., 1990) volume 21.