Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/49

 that to move towards this, is a moving towards that of the World, that he cannot affirm, unless he supposeth, That the Centre of the Earth, from which we see these light ascendent bodies to depart, be the same with the Centre of the World; which is as much as to say, that the terrestrial Globe is constituted in the midst of the World: which is yet that of which we were in doubt, and which Aristotle intended to prove. And do you say that this is not a manifest Paralogism?

This Argument of Aristotle appeared to me deficient also, and non-concludent for another respect; though it were granted, that that Circumference, to which the Fire directly moveth, be that which includeth the World: for that in a circle, not onely the centre, but any other point being taken, every moveable which departing thence, shall move in a right line, and towards any whatsoever part, shall without any doubt go towards the circumference, and continuing the motion, shall also arrive thither; so that we may truly say, that it moveth towards the circumference: but yet it doth not follow, that that which moveth by the same line with a contrary motion, would go towards the centre, unless when the point taken were the centre it self, or that the motion were made by that onely line, which produced from the point assigned, passeth thorow the centre. So that to say, that Fire moving in a right line, goeth towards the circumference of the World, therefore the parts of the Earth which by the same lines move with a contrary motion, go towards the centre of the World, concludeth not, unless then when it is presupposed, that the lines of the Fire prolonged pass by the centre of the World; and because we know certainly of them, that they pass by the centre of the Terrestrial Globe (being perpendicular to its superficies, and not inclined) therefore to conclude, it must be supposed, that the centre of the Earth is the same with the centre of the World; or at least, that the parts of the Fire and Earth descend not, save onely by one sole line which passeth by the centre of the World. Which nevertheless is false, and repugnant to experience, which sheweth us, that the parts of Fire, not by one line onely, but by infinite, produced from the centre of the Earth towards all the parts of the World, ascend always by lines perpendicular to the Superficies of the Terrestrial Globe.

You do very ingeniously lead Aristotle to the same inconvenience, Sagredus, shewing his manifest equivoke; but withal you add another inconsistency. We see the Earth to be spherical, and therefore are certain that it hath its centre, to which we see all its parts are moved; for so we must say, whilst their motions are all perpendicular to the Superficies of the Earth; we