  The combination of meticulous field observation, collection and experimentation, note taking, reading and thinking during what turned into the Beagle’s five year journey through a very wide cross-section of the earth’s environments was to set the course for the rest of his life. During the voyage he read and reread Charles Lyell’s newly published Principles of Geology, a three-volume work that articulated a philosophical vision of rigorously empirical historical science, oriented around five key ideas: