The Renaissance was a modern and secular period of history, characterized by the emergence of Humanism, which was a movement based on reviving Grecco-Roman literary works. Humanism was associated with individualism and secularism, and the art throughout the Renaissance reflected these values with nudity, portraiture, and a more acute awareness of personal identity. Humanism was the study of ancient Grecco-Roman literary works, and scholars read ancient literary works.
The Renaissance was drastically different from the Renaissance. The Renaissance was full of illiteracy and loss of technology, rural manors (few cities), violent nobles, serfdom, and church monopoly. It was a "dark age" in the eyes of Renaissance scholars. With the Crisis of the 14th century full of population catastrophe from the black death, the Hundred Years was, and the Avignon Papacy, the Renaissance was a drastic change from this backwards time. This segues to Greenblatt's theory of the Renaissance.
Greenblatt's characterizes the Renaissance as an era of rediscovery, secular ideas, knowledge, communication, understanding, antiquity. Greenblatt believes that the rediscovery of Lucretius''s ideas in "On the Nature of Things" was the most momentus moment. It contained the idea of atoms, and the rediscovery of this theory was huge. It also contained ideas of individualism and striving to find your own happiness and success. Greenblatt believed that the Renaissance was the beginning of the modern world. He believed the period before it was a Dark Age of religion, and the Renaissance was when Europe drastically changed as religion lost its superiority and ancient ideas were uncovered and put into place.
The Renaissance did not apply to most people, however. The Renaissance was only impactful to the upper class elites. The lower class people would hardly even know it was happening. They were still religious.