 Complete the following phrase:  Charles Darwins studies at the University of Cambridge included two other texts by Paley, and in his final exams in January 1831 he did well in questions on these texts. He had to stay on until June, and read Paleys Natural Theology as well as John Herschels Preliminary Discourse on the Study of Natural Philosophy and Alexander von Humboldts Personal Narrative: these books inspired a burning zeal to research natural history. After the 