ſhould be without it; the Argument being of much greater force in them, by reaſon of the daily Eclipſes of their Moons, and the frequent ones of the Sun to their Inhabitants. So that if a Perſon diſintereſted in his Judgment, and equally ignorant of the Affairs of all the Planets, were to give his Opinion in this Matter, I don’t doubt he would give the Cauſe for Aſtronomy to thoſe two Planets rather than us. This Suppoſition of their Knowledge and Uſe of Aſtronomy in the Planetary Worlds, will afford us many new Conjectures about their manner of Life, and their State as to other things. [And all its ſubſervient Arts.] For, Firſt: No Obſervations of the Stars that are neceſſary to the Knowledge of their Motions, can be made without Inſtruments; nor can theſe be made without Metal, Wood, or ſome ſuch ſolid Body. Here’s a neceſſity of allowing them the Carpenters Tools, the Saw, the Ax, the Plane, the Mallet, the File: and the making of theſe requires the Uſe of Iron, or ſome equally hard Metal. [Geometry and Arithmetick:] Again, theſe Inſtruments can’t be without a Circle divided into equal Parts, or a ſtrait Line into unequal. Here’s a neceſſity for introducing Geometry and Arithmetick. Then the Neceſſity [And Writing.] in ſuch Obſervations of marking down the Epochas or Accounts of Time, and of tranſmitting them to Poſterity, will force us to grant them the Art of Writing; perhaps very different from ours which is commonly uſed, but I dare affirm not more ingenious or eaſy. For how much more ready and expeditious is our Way, than by that multitude of Characters uſed in China; and how vaſtly preferable to Knots tied in Cords, or the Pictures in uſe among the barbarous People of Mexico and Peru? There’s no Nation in the World but has ſome way or other of writing or marking down their Thoughts: So that it’s no wonder if the Planetary Inhabitants have been taught it by that great School-miſtreſs Neceſſity, and apply it to the Study of Aſtronomy and other Sciences. In Aſtronomical Matters the Neceſſity of it is moreover apparent from hence, that the Motion of the Stars is as ’twere to be fancied and gueſs’d at in different Syſtems, and theſe Syſtems to be continually improved and corrected, as later and more exact Obſervations ſhall convince the old ones of Faults: all which can never be deliver’d down to ſucceeding Generations, unleſs we make uſe of Letters and Figures.