magnitude; in presenting forms which are determined, and limits which are perceived by the senses, one conceives, easily, without its being necessary to study this last question directly, that this would be the consequence of the contrary supposition, and that consequently, one must come to look at every object as infinite.
“One must also admit, that the most minute particle perceptible to the sense, is neither absolutely like the objects which are susceptible of transformation, nor absolutely different from them. It has some characteristics in common with the object which admit of transformation, but it also differs from them, inasmuch as it does not allow any distinct parts to be discerned in it. When then, in virtue of these common characteristics, and of this resemblance, we wish to form an idea of the smallest particle perceptible by the senses, in taking the objects which change for our terms of comparison, it is necessary that we should seize on some characteristic common to these different objects. In this way, we examine them successively, from the first to the last, not by themselves, nor as composed of parts in juxtaposition, but only in their extent; in other words, we consider the magnitudes by themselves, and in an abstract manner, inasmuch as they measure, the greater a greater extent, and the smaller a smaller extent. This analogy applies to the atom, as far as we consider it as having the smallest dimensions possible. Evidently by its minuteness, it differs from all sensible objects, still this analogy is applicable to it; in a word, we establish by this comparison, that the atom really has some extent, but we exclude all considerable dimensions, for the sake of only investing it with the smallest proportions.4
“We must also admit, in taking for our guide, the reasoning which discourses to us things which are invisible to the senses, that the most minute magnitudes, those which are not compound magnitudes, and which from the limit of sensible extent, are the first measure of the other magnitudes which are only