An excerpt from one of Galileo Galilei's letters to Don Virginio Cesarini:
Long experience has taught me this about the status of mankind with regard to matters requiring thought: the less people know and understand about them, the more positively they attempt to argue concerning them, while on the other hand to know and understand a multitude of things renders men cautious in passing judgment upon anything new.
Want more Galileo? The Istituto e Museo di Storia della Scienza in Florence is loaning out their exhibit, Galileo, the Medici and the Age of Astronomy to The Franklin in Philadelphia. It features one of the last two telescopes belonging to the astronomer, as well as his notes, paintings, and other instruments, including the cylindrical sundial and Michelangelo's compass.