Neil Livingstone was a Sunday school teacher and teetotaller who handed out Christian tracts on his travels as a door-to-door tea salesman. He read books on theology, travel, and missionary enterprises extensively. This rubbed off on the young David, who became an avid reader, but he also loved scouring the countryside for animal, plant, and geological specimens in local limestone quarries. Neil feared that science books were undermining Christianity and attempted to force his son to read nothing but theology, but David's deep interest in nature and science led him to investigate the relationship between religion and science. In 1832, he read "Philosophy of a Future State", written by Thomas Dick, and he found the rationale that he needed to reconcile faith and science and, apart from the Bible, this book was perhaps his greatest philosophical influence.