The Journal, as a plot device, was maybe inspired by Tolkien and his Red Book of the Westmarch that is supposedly the ultimate source of Lord of the Rings and his other works. Similar tricks were used by other, earlier sci-fi and fantasy authors. For example, Frank Herbert opened each chapter of his first Dune novel with quotations from texts based on sayings and teachings of the main characters and groups/societies and the adventures of Sherlock Holmes were published in the form of narrations by Dr. Watson.