John Cassian
In Christianity early Church Fathers appeared to use the idea of a book of nature, librum naturae, as part of a two-book theology: "Among the Fathers of the Church, explicit references to the Book of Nature can be found, in St. Basil, St. Gregory of Nyssa, St. Augustine, John Cassian, St. John Chrysostom, St. Ephrem the Syrian, St. Maximus the Confessor."