Biographies of André Michaux and his own work depict him more as a man of action than of contemplation. A careful reading of his writings, however, reveals not only a busy botanist but also a sensitive observer of religions, not only an intrepid explorer but also a man possessed of some fears. This paper examines Michaux's worldview that underlay his complex character, his understanding of God and nature as evidenced in his journals and letters. It offers the thesis that Michaux's religion intriguingly combined Enlightenment Natural Religion with popular French Catholic piety.