is more known than the posterior, as a point than a line, and a line than a superficies, and a superficies than a solid, as also unity than number, for it is prior to, and the principle of, all number; likewise a letter than a syllable. Nevertheless, to us, the reverse sometimes happens, since a solid falls under sense rather than a superficies, but a superficies more than a line, and a line more than a point, for the multitude know these things in a greater degree, since some things it is possible for any casual intellect to discern, but others belong to an intellect accurate and transcendent.
Simply then, it is better to aim at the knowledge of things posterior through such as are prior, for a thing of this kind is more scientific; still by those who are incapable of knowing through things of this kind, it is perhaps necessary to frame the definition through things known to them. Now of such definitions, are those of a point, and of a line, and of a superficies, for all manifest things prior, through such as are posterior, for they say that one is the boundary of a line, the other of a superficies, and the other of a solid. Still we must not be unmindful that those who define thus, cannot denote what the nature is of the thing defined, unless the same thing should happen both to be more known to us, and simply to be more known, since he who well defines must necessarily do so, through the genus and the differences, but these are of the number of things more known simply than, and prior to, species. For genus and difference co-subvert species, so that these are prior to species. They are also more known, for if species is known, it is necessary that genus also and difference should be known, (as he who knows man, knows both animal and pedestrian,) but when genus or difference is known, it is not necessary that species also should be known, wherefore species is more unknown. Besides, to those who really call things of this kind, definitions, which
