Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/255

 necessity suspect our own senses, as wholly fallible, or stupid in judging of sensible things even very near at hand. What truth therefore can we hope for, to be derived from so deceiveable a faculty?

But I desire not to deduce precepts more profitable, or more certain, learning to be more circumspect and less confident about that which at first blush is represented to us by the senses, which may easily deceive us. And I would not have this Author trouble himself in attempting to make us comprehend by sense, that this motion of descending Graves is simply right, and of no other kind; nor let him exclaim that a thing so clear, manifest, and obvious should be brought in question; for in so doing, he maketh others believe, that he thinketh those that deny that motion to be absolutely streight, but rather circular, the stone did sensibly see it to move in an arch, seeing that he inviteth their senses more than their Reason, to judg of that effect: which is not true, Simplicius, for like as I, that am indifferent in all these opinions, and onely in the manner of a Comedian, personate Copernicus in these our representations, have never seen, nor thought that I have seen that stone fall otherwise than perpendicularly, so I believe, that to the eyes of all others it seemed to do the same. Better it is therefore, that deposing that appearance in which all agree, we make use of our Reason, either to confirm the reality of that, or to discover its fallacy.

If I could any time meet with this Philosopher, who yet me thinks is more sublime than the rest of the followers of the same doctrines, I would in token of my affection put him in mind of an accident which he hath doubtless very often beheld; from which, with great conformity to that which we now discourse of, it may be collected how easily one may be deceived by the bare appearance, or, if you will, representation of the sense. And the accident is, the Moons seeming to follow those that walk the streets in the night, with a pace equal to theirs, whilst they see it go gliding along the Roofs of houses, upon which it sheweth just like a cat, that really running along the ridges of houses, leaveth them behind. An appearance that, did not reason interpose, would but too manifestly delude the sight.

Indeed there want not experiments that render us certain of the fallacy of the meer senses; therefore suspending such sensations for the present, let us hear the Arguments that follow which are taken, as he saith, ex rerum naturâ. The first of which is, that the Earth cannot of its own nature move with three motions very different; or otherwise we must deny many manifest Axioms. The first whereof is, that Omnis effectus dependeat ab aliquâ causà; [i. e.] that every effect dependeth on some cause.