tained of the milky way, when, the weakness of their vision not having yet received the assistance of art, they attributed this color to a greater density in that part of the heavens which reflected the light more strongly? But would we not be inexcusable for remaining in the same opinion, now that, by the aid of the advantages procured us by the telescope, we have discovered in it an infinite number of small stars, whose more abundant splendor has revealed to us the true cause of this whiteness!
Had they not also cause for saying that all corruptible bodies were inclosed within the orbit of the moon, when, during the course of so many ages they had not yet remarked either corruption or generation outside of this space?
But ought we not to be assured of the contrary, when the whole world has manifestly beheld comets kindle and disappear far beyond the limits of that sphere?
In the same way, in respect to vacuum, they had a right to say that nature would not suffer it, since all their experiments had always made them remark that she abhorred, and could not suffer it.
| But if the modern experiments had been known to them, perhaps they would have found cause for affirming what they found cause for denying, for the reason that vacuum had not yet appeared. Thus, in the judgment they formed that nature would not suffer vacuum, they only heard nature spoken of in the condition in which they knew her; since, to speak in general terms, it would not have been sufficient to have seen it constantly in a hundred cases, a thousand, or any other number, however great it may have been; since, if a single case remained unexamined, this alone would suffice to prevent the general definition, and if a single one was contrary, this alone |
For in all matters the proof of which consists in experiments, and not in demonstrations, we can make no universal assertion, except by the general enumeration of all the parts and all the different cases. Thus it is that when we say that the diamond is the hardest of all bodies, we mean of all the bodies with which we are acquainted, and we neither can nor ought to comprehend in this assertion those with which we are not acquainted; and when we say that gold is the heaviest
