He therefore knocks, and beats it with flints, to see what was discoverable in the inside: he finds it yield to blows, but not easily separate into pieces: he finds it will bend without breaking.

Is not now ductility to be added to his former idea, and made part of the essence of the species that name ZAHAB stands for?
Further trials discover fusibility and fixedness.

Are not they also, by the same reason that any of the others were, to be put into the complex idea signified by the name ZAHAB?
If not, what reason will there be shown more for the one than the other?
If these must, then all the other properties, which any further trials shall discover in this matter, ought by the same reason to make a part of the ingredients of the complex idea which the name ZAHAB stands for, and so be the essence of the species marked by that name.

Which properties, because they are endless, it is plain that the idea made after this fashion, by this archetype, will be always inadequate.
48.

The Abstract Ideas of Substances always imperfect and therefore various.
But this is not all.