The rise of the printing press meant that nobility and clergy could afford more books, but it also appeared at a very opportune time. A new merchant class was on the rise in Europe. These were people who had not been born into wealth but had made money as merchants and craftspeople. The printing press meant that these people, for the first time, could afford books for themselves and their children. This brought about a greatly increased interest in education and caused the middle class to grow.
The first book to be printed and the most popular was the Bible. As books became less expensive, though, there was demand for more books, including secular books. This meant that books on philosophy, science, economics, history and even works of fiction began to be printed. This allowed the spread of new ideas beyond the few universities and learning centers that existed at the time for Europe's nobility and growing middle class. It also meant that thinkers and scholars of the era were able to begin writing and publishing new works.
Prior to the invention of the printing press, the Bible was the exclusive property of the Catholic Church. Not only were copies of the Bible rare and expensive but they were also written in Latin, a language that few outside the clergy could understand. With the invention of the printing press, not only was the Bible more widely available, but it began to be translated and printed in other languages. This allowed people to read and think about the Bible and religion for themselves for the first time and led to new interpretations. The printing press is believed by most historians to have directly caused the Reformation and the birth of the Protestant churches.
It is unclear whether the printing press led to the Renaissance or merely contributed to it, but it is clear that the ease with which ideas and information spread helped the Italian Renaissance move to the rest of Europe. For the first time since ancient Rome, people were openly exploring ideas, the world around them and religion itself. It is this exploration that defined the Renaissance period, and it would not have been possible without the printing press.
The explorations of the Renaissance led directly to the Scientific Revolution and the Age of Enlightenment. This era saw the beginnings of many of modern ideas about science and politics, including the social contract, democratic and representative government, capitalism, equality and human rights. The political ideas of the Enlightenment were what gave rise to democratic revolutions in Europe and to the American Revolution. The Declaration of Independence is very much inspired by the philosophies of the age of Enlightenment.
The printing press, which allowed everyone to read, gave rise to the middle class, the Reformation, the Renaissance, the Scientific Revolution and the Age of Enlightenment. Now there is the Internet, which allows nearly everyone not only to read ideas, but to share their own stories, ideas, and experiences with the world, nearly for free. Who knows what this new technology will lead to.