The discovery of a world in the moone

by John Wilkins

Either the argument from the paralax is not efficacious, or if it be, yet the use of the instruments might deceive either in regard of the starre or the medium, or the distance, and so this comet might be in the upper regions of the aire, or if it were in the heavens, there it might be produced by the reflexion of the rayes from Saturne and Jupiter, who were then in conjunction.

You see what shifts hee is driven to, how he runnes up and downe to many starting holes, that hee may find some shelter, and in stead of the strength of reason, he answers with a multitude of words, thinking (as the Proverbe is) that hee may use haile, when hee hath no thunder, Nihil turpius (saith * Epist. 95. *Seneca) dubio est incerto, pedem modo referente, modo producente.

What can there bee more unseemely in one that should be a faire disputant, then to be now here, now there, and so uncertaine, that one cannot tell where to find him.

He thinkes that there are not Comets in the heavens, because there may be many other reasons of such appearances, but what he knowes not, perhaps (he saies) that argument from the parallax is not sufficient, or if it be, then there may be some deceit in the observation. To this I may safely say, that hee may justly be accounted a weake Mathematician who mistrusts the strength of this argument, nor can hee know much in Astronomy, who understands not the parallax, which is the foundation of that Science, and I am sure that hee is a timorous man, who dares not believe the frequent experience of his senses, or trust to a demonstration.

True indeed, I grant tis possible, that the eye, the medium, and the distance may al deceive the beholder, but I would have him shew which of all these was likely to cause an error in this observation? Meerely to say they might be deceived is no sufficient answer, for by this I might confute the positions of all Astronomers, and affirme the starres are hard by us, because ’tis possible they may be deceived in their observing that distance. But I forbeare any further reply; my opinion is of that Treatise, that either it was set forth purposely to tempt a confutation, that hee might see the opinion of Galilæus confirmed by others, or else it was invented with as much haste and negligence as it was printed, there being in it almost as many faults as lines.

Others thinke that these are not any new Comets, but some ancient starres that were there before, which now shine with that unusuall brightnesse, by reason of the interposition of such vapors which doe multiply their light, and so the alteration will be here onely, and not in the heavens. Thus Aristotle thought the appearance of the milkie way was produced, for he held that there were many little starres, which by their influence did constantly attract such a vapour towards that place of heaven, so that it alwaies appeared white. Now by the same reason may a brighter vapor be the cause of these appearances.

But how probable soever this opinion may seeme, yet if well considered, you shall finde it to be altogether absurd and impossible: for,

1. These starres were never seene there before, and tis not likely that a vapour being hard by us can so multiply that light which could not before be at all discerned.

2. This supposed vapour cannot be either contracted into a narrow compasse or dilated into a broad: 1. it could not be within a little space, for then that starre would not appeare with the same multiplied light to those in other climates: 2. it cannot be a dilated vapour, for then other starres which were discerned through the same vapour would seeme as bigg as that; this argument is the same in effect with that of the paralax, as you may see in this Figure.