Before the Scientific Revolution, this method of gaining knowledge was uncommon. Some of the main ideas of science had been expressed long before the Scientific Revolution. In fact, some of the basic ideas of science are ancient. Many Greek thinkers expressed ideas that, today, we would call scientific. Before the Scientific Revolution, most educated people who studied the world took guidance from the explanations given by authorities like ancient Greek writers and Catholic Church officials. After the Scientific Revolution, educated people placed more importance on what they observed and less on what they were told.