The correct answer is Humanism. According to the Internet Encyclopedia of Philosophy, "Although Machiavelli studied ancient humanists, he does not often cite them as authorities". It also says "But there was certainly a widespread and effervescent revival of Platonism in Florence before and during Machiavelli’s lifetime". So, even though Machiavelli´s ideas were the opposite of Plato´s ideas. At that time, The Renaissance, the influence os Plato´s thought was effervescent among intellectuals and artists. So, Machiavelli was an innovator in his ideas, specially about political sciences, but he was influenced by his time and others philosophes who come before him.