Tis reported of Aristotle, that when he saw the Books of Moses, hee commended them for such a majestick stile as might become a God, but withall hee censured that manner of writing to be very unfitting for a Philosopher; because there was nothing proved in them, but matters were delivered as if they would rather command than perswade beliefe. And ‘tis observed that hee sets downe nothing himselfe, but hee confirmes it by the strongest reasons that may be found, there being scarce an argument of force for any subject in Philosophy, which may not be picked out of his Writings; and therefore ‘tis likely if there were in reason a necessity of one onely world, that hee would have found out some such necessary proofe as might confirme it: Especially since hee labours for it so much in two whole Chapters. But now all the arguments which hee himselfe urges in this subject,1 are very weake, and farre enough from having in them any convincing power. Therefore ‘tis likely that a plurality of worlds doth not contradict any principle of reason. However, I will set downe the two chiefe of his arguments from his owne works, and from them you may guesse the force of the other.
The first is this, (Ibid) since every heavie body doth naturally tend downwards, and every light body upwards, what a hudling and confusion must there be if there were two places for gravity, and two places for lightnesse: for it is probable that the earth of that other world would fall down to this Center, and so mutually the ayre and fire here ascend to those Regions in the other, which must needs much derogate from the providence of nature, and cause a great disorder in his works. But ratio haec est minimè firma,2 (saith Zanchy) And if you well consider the nature of gravity, you will plainely see there is no ground to feare any such confusion; for heavinesse is nothing else but such a quality as causes a propension in its subject to tend downwards towards its owne Center; so that for some of that earth to come hither, would not be said a fall but an ascension, since it moved from its own place, and this would be impossible (saith Ruvio) because against nature, and therefore no more to be feared than the falling of the Heavens.3
If you reply that then according to this, there must be more Centers of gravity than one; I answer. ‘Tis very probable there are, nor can we well conceive, what any piece of the Moon would doe being severed from the rest in the free and open ayre, but only returne unto it againe.
Another argument hee had from his Master Plato,4 that there is but one world,5 because there is but one first mover, God.
Infirma etiam est haec ratio (saith Zanchy) and we may justly deny the consequence, since a plurality of worlds doth not take away the unity of the first mover. Vt enim forma substantialis, sic primum efficiens apparentem solummodo multiplicitatem induìt per signatam materiam (saith a Country-man of ours.)6 As the substantiall forme, so the efficient cause hath only an appearing multiplicity from its particular matter. You may see this point more largely handled, and these Arguments more fully answered by Plutarch in his booke (why Oracles are silent) and Iacob Carpentarius in his comment on Alcinous.
But our opposites the Interpreters themselves, (who too often doe jurare in verba magistri) will grant that there is not any strength in these consequences, and certainly then such weake arguments could not covince that wise Philosopher, who in his other opinions was wont to be swayed by the strength and power of reason: wherefore I should rather think that he had some by-respect, which made him first assent to this opinion, and afterwards strive to prove it. Perhaps it was because hee feared to displease his scholler Alexander, of whom ‘tis related that he wept to heare a disputation of another world,7 since he had not then attained the Monarchy of this; his restlesse wide heart would have esteemed this Globe of Earth not big enough for him, if there had beene another, which made the Satyrist say of him, Aestuat infoelix angusto limite mundi. (Iuvenal)