The Frontispiece has an "Explication" in French. Here is an English translation:

Under a Temple in the Ionic style, Sanctuary of Truth, we see Truth wrapped in a veil, and radiant with a light that removes the clouds and disperses them. To the right of Truth, stand Reason and Philosophy; the former lifts, the latter pulls at the veil of Truth. At her feet, Theology, kneeling, receives her light from on high. By following the chain of figures, on the same side [as Reason and Philosophy] one finds Memory, Ancient History and Modern History. [Modern] History is writing the annals, and Time himself serves as a support. Below [these figures] are grouped Geometry, Astronomy and Physics. The figures below this group show Optics, Botany, Chemistry and Agriculture. At the very bottom are more Arts and Professions that emanate from the Sciences. To the left of Truth, one sees Imagination, who prepares to beautify and crown Truth [with flowers]. Below Imagination, the designer has placed the different kinds of Poetry: Epic, Dramatic, Satirical, Pastoral. Then come the other Arts of Imitation, Music, Painting, Sculpture and Architecture.