Whether the essays were written to support the author’s theological studies, as material to be presented in convocations, or in response to the scientific revelations or debates of the time is unclear; however, a reader with initials “J.W.M” read, notated, and provided short comments on the contents. Cilley provided a few ink drawings, including a chart showing the geologic strata and time periods, as well as an image of the human heart. Many essays contain citations to theological writings of the period. Among the many philosophers and writers covered are Aristotle, Benedict Spinoza, Thomas Hobbes, d’Alembart, Diderot, Voltaire, Alexander Pope, David Hume, Hugh Miller, and Enoch Pond.