If we lived on a planet where nothing ever changed, there would be little to do. There would be nothing to figure out. There would be no impetus for science. And if we lived in an unpredictable world, where things changed in random or very complex ways, we would not be able to figure things out. ___________________________. If I throw a stick up in the air, it always falls down. If the sun sets in the west, it always rises again the next morning in the east. And so it becomes possible to figure things out. We can do science, and with it we can improve our lives."

_{Carl Sagan, http://todayinsci.com/S/Sagan_Carl/SaganCarl-Quotations.htm Acessado em 14 de Abril de 2015.}