The Observable Cosmos & The Unobservable Cosmos is the sixth entry in the Little Blue Book Series and comprises of the eleventh to twelfth discourses of the Monodoxy, which is itself the first disquisition of the founding book of Astronism which is titled the Omnidoxy. The Observable Cosmos & The Unobservable Cosmos discourse explores the notion that there exists four perceptual dimensions of The Cosmos; The Observable Cosmos, The Unobservable Cosmos as well as The Knowable Cosmos and The Unknowable Cosmos. This forms the important Astronic cosmology theory and belief of tetradimensionalism.
 
The Little Blue Book Series was created and first published by Cometan himself as a way to simplify and commercialise the immensity of the two million word length of the Omnidoxy into smaller, more bite-size publications. A successful series from its very first published entry, the Little Blue Book Series has gone on to become a symbol of Astronist commercial literature and a way for Cometan’s words to reach readers of all ages and abilities who remain daunted by the beauty and yet the sheer extensiveness of the Omnidoxy as the longest religious text in history.