To understand an author’s developmental trajectory, the static traits and properties of author reconstruction and profiling are not sufficient. Instead, it is necessary to focus on high-level indicators of the complex set of variables that underlie the author’s transient mental states during his or her creative production. We propose a method that combines information theory with random fractal theory to study the mental dynamics of an author as indicated by text complexity. To illustrate its application, we analyze the developmental trajectory of the culturally influential and ‘graphomanic’ 19th-century Danish pastor N. F. S. Grundtvig. This approach can detect an age-related trend (entropic decay), a significant Kehre (turning point), and multiple event-related change points in his production. We argue that the approach is applicable beyond the specific case and can be extended to comparative analysis within and between authors, and, finally, to dynamic analysis of cultural information systems.