5. The only essences perceived by us in individual substances are those qualities which entitle them to receive
their names.
Thus, if the idea of body with some people be bare extension or space, then solidity is not essential to
body: if others make the idea to which they give the name body to be solidity and extension, then solidity is
essential to body. That therefore, and that alone, is considered as essential, which makes a part of the complex
idea the name of a sort stands for: without which no particular thing can be reckoned of that sort, nor be entitled to
that name. Should there be found a parcel of matter that had all the other qualities that are in iron, but wanted
obedience to the loadstone, and would neither be drawn by it nor receive direction from it, would any one
question whether it wanted anything essential? It would be absurd to ask, Whether a thing really existing wanted
anything essential to it. Or could it be demanded, Whether this made an essential or specific difference or no,
since we have no other measure of essential or specific but our abstract ideas? And to talk of specific differences
in nature, without reference to general ideas in names, is to talk unintelligibly. For I would ask any one, What is
sufficient to make an essential difference in nature between any two particular beings, without any regard had to
some abstract idea, which is looked upon as the essence and standard of a species? All such patterns and standards
being quite laid aside, particular beings, considered barely in themselves, will be found to have all their qualities
equally essential; and everything in each individual will be essential to it; or, which is more, nothing at all. For,
though it may be reasonable to ask, Whether obeying the magnet be essential to iron? yet I think it is very
improper and insignificant to ask, whether it be essential to the particular parcel of matter I cut my pen with;
without considering it under the name iron, or as being of a certain species. And if, as has been said, our abstract
ideas, which have names annexed to them, are the boundaries of species, nothing can be essential but what is
contained in those ideas.
