Whether one sees the Renaissance as a period of originality or just drawing upon older cultures, it did generate four ideas that have been and still are central to Western Civilization: secularism, humanism, individualism, and skepticism.
Secularism comes from the word secular, meaning of this world. Medieval civilization had been largely concerned with religion and the next world. The new economic and political horizons and opportunities that were opening up for Western Europe in the High and Late Middle Ages got people more interested in this world. During the Renaissance people saw this life as worth living for its own sake, not just as preparation for the next world. The art in particular exhibited this secular spirit, showing detailed and accurate scenery, anatomy, and nature, whereas medieval artists generally ignored such things since their paintings were for the glory of God. This is not to say that Renaissance people had lost faith in God. Religion was still the most popular theme for paintings. But during the Renaissance people found other things worth living for besides the afterlife.
Humanism goes along with secularism in that it makes human beings, not God, the center of attention. The quotation at the top of this reading certainly emphasizes this point. So did Renaissance art, which portrayed the human body as a thing of beauty in its own right, not like some medieval "comic strip" character whose only reason to exist was for the glory of God. Along those lines, Renaissance philosophers saw humans as intelligent creatures capable of reason (and questioning authority) rather than being mindless pawns helplessly manipulated by God. Even the term for Renaissance philosophers, "humanists", shows how the focus of peoples' attention had shifted from Heaven and God to this world and human beings. It also described the group of scholars who drew upon the more secular Greek and Roman civilizations for inspiration.
Individualism takes humanism a step further by saying that individual humans were capable of great accomplishments. The more communal, group oriented society and mentality of the Middle Ages was giving way to a belief in the individual and his achievements. The importance of this was that it freed remarkable individuals and geniuses, such as Leonardo da Vinci to live up to their potential without being held back by a medieval society that discouraged innovation. Besides the outstanding achievements of Leonardo, one sees individualism expressed in a wide variety of ways during the Renaissance. Artists started signing their paintings, thus showing individualistic pride in their work. Also, the more communal guild system was being replaced by the more individualistic system of capitalism, which encouraged private enterprise.
4. Skepticism, which promoted curiosity and the questioning of authority, was largely an outgrowth of the other three Renaissance ideas. The secular spirit of the age naturally put Renaissance humanists at odds with the Church and its purely religious values and explanations of the universe. Humanism and individualism, with their belief in the ability of human reason, raised challenges to the Church's authority and theories, which in turn led to such things as the Protestant Reformation, the Age of Exploration and the Scientific Revolution, all of which would radically alter how Western Europe views the world and universe. These four new ideas of secularism, humanism, individualism, and skepticism led to innovations in a variety of fields during the Renaissance, the most prominent being literature and learning, art, science, the Age of Exploration, and the Protestant Reformation.