Renaissance humanism is considered to have first developed in Florence, Italy, beginning in the 14thC. for a variety of reasons, and perhaps the two most important are the rise of the Medici family, whose patronage of the arts and literature profoundly affected the intellectual atmosphere of Florence; and the fall of Constantinople in 1453 to the Turks, which brought additional Greek and Roman classical literature and philosophies to Florence and western Europe. The Renaissance marks the evolution of the medieval world to the modern, and one of the most important aspects of this change is the rise of humanism, broadly defined as a shift away from a belief that God and the church define man to the new conviction that mankind and his institutions--life on earth and in the present, not life after death--is man's chief concern.
Machiavelli's The Prince (1513, 1532), a product of the new mankind-centered world view, is a leadership manual based on a realistic view of man's nature--social, political, intellectual--rather than the church-inspired belief that man is and should be constantly reaching for the Christian ideal of himself. Machiavelli signals the shift from the religious ideal to the practical and worldly when he advises a leader that
. . . whether it be better to be loved than feared or feared than loved? It may be answered that one should wish to be both, but, because it is difficult to unite them in one person, it is much safer to be feared than loved, when, of the two, either must be dispensed with. (17:4)
The Christian ideal of the leader who is loved and admired because his actions are animated by religious convictions has been replaced by a leader who, if he cannot be both feared and loved, must choose to rule by fear, not because fear is inherently the best choice, but because men are
. . . are ungrateful, fickle, false, cowardly, covetous, and as long as you succeed they are yours entirely; they will offer you their blood, property, life, and children, as is said above, when the need is far distant; but when it approaches they turn against you. (17:4)
This passage has been condemned since the publication of The Prince for its cynical (also, practical) assumption that men's nature is essentially base and cowardly. Machiavelli's advice is not based on a belief that man is constantly seeking the good but that his nature is "fickle, cowardly, covetous." A leader of such people, then, can be effective only through the exercise of fear, which is a very modern concept because it ignores the possibility that mankind strives for the Christian ideal to guide his behavior.
Like Dante, a century before him, who looked to Virgil to guide him through Hell and back (The Divine Comedy), Machiavelli read widely in Greek and Roman history, literature, and philosophy and applied the leadership guidelines of the pre-Christian era to create a new political philosophy. For example, in his discussion of whether a new prince can avoid the perception of cruelty, Machiavelli quotes Queen Dido, who explains:
To bring about a new kingdom, when conditions are hard, I am compelled to do cruel things to insure the [proper] ends. (17:1) (My translation)
In other words, Machiavelli looks to a Greek queen to draw the conclusion that, for a greater good, the end may indeed justify the means, a concept that is thoroughly modern, arises from humanism, but has seriously negative possibilities, particularly if evil leaders decide what is or isn't "the greater good."
Throughout The Prince, Machiavelli refers to pre-Christian leaders whose stories originate in classical Greek and Roman literature and history. In Chapter 8, Machiavelli discusses leaders who have achieved greatness not through heredity or fortune but because of natural abilities--Moses, Cyrus, Romulus, Theseus. These models derive from biblical sources, Greek and Roman mythology, and, in the case of Cyrus, the Greek historian Xenophon's Life of Cyrus--sources that became widely known only at the beginning of the 14thC. when Renaissance humanism began to evolve.