The engraving of the pre-title page shows the subject of the book - an astronomical treatise on comets - and the author's observatory. The historical views on the origin and orbits of the planets are also depicted: on the left is Aristotle (384 BC - 322 BC), on the right is Johann Kepler (1571-1630), and in the middle is the author of the treatise, Johann Hevelius (1611-1687).