28. Wandering stars far more truly than the planets which have received this etymological designation, the comets should be the guides leading us over the limits of the system, to which the Earth belongs, carrying us into the far-away regions of sidereal space.
But, before exploring by the aid of these travelers of the universe the celestial domains, it will be well for us to become acquainted as much as possible with their intrinsic nature and their role in the planetary economy.
