Nobody will doubt that the wheels or springs (if I may so say) within, are different in a RATIONAL MAN and a CHANGELING; no more than that there is a difference in the frame between a DRILL and a CHANGELING.

But whether one or both these differences be essential or specifical, is only to be known to us by their agreement or disagreement with the complex idea that the name man stands for: for by that alone can it be determined whether one, or both, or neither of those be a man.
40.

Species of Artificial Things less confused than Natural.
From what has been before said, we may see the reason why, in the species of artificial things, there is generally less confusion and uncertainty than in natural.

Because an artificial thing being a production of man, which the artificer designed, and therefore well knows the idea of, the name of it is supposed to stand for no other idea, nor to import any other essence, than what is certainly to be known, and easy enough to be apprehended.

For the idea or essence of the several sorts of artificial things, consisting for the most part in nothing but the determinate figure of sensible parts, and sometimes motion depending thereon, which the artificer fashions in matter, such as he finds for his turn; it is not beyond the reach of our faculties to attain a certain idea thereof; and so settle the signification of the names whereby the species of artificial things are distinguished, with less doubt, obscurity, and equivocation than we can in things natural, whose differences and operations depend upon contrivances beyond the reach of our discoveries.
41.