Machievalli is a modern thinker. It means that he did not hold medieval view on human nature. He was absolutely aware of unethical (unethical or amoral from the perspective of Christian morality) aspect of human nature. Humans have their ethical principles, but in fact their own nature is much more different and sometimes he/she can follow amoral principles (from the Christian point of view) and his/her actions can be effective. So, to be effective sometimes it is necessary to be unethical. This is a pure pragmatism that is required in politics. In this respect Machiavelli is a modern thinker.
Explanation: Machiavelli was quite ahead of his time, because he did not work with exaggerated ideals (Christian concept of human being contains exaggerated criterions for human behaviour). Politics and morals do not go hand in hand.