 Natural philosophers (i.e. scientists) come along later to try to determine if the connections between properties which the ordinary folk have put together in a particular idea in fact holds in nature. Scientists are seeking to find the necessary connections between properties. Still, even scientists, in Locke’s view, are restricted to using observable (and mainly secondary) qualities to categorize things in nature. Sometimes, the scientists may find that the ordinary folk had erred, as when they called whales ‘fish’. A whale is not a fish, as it turns out, but a mammal. There is a characteristic group of qualities that fish have that whales do not have. There is a characteristic group of qualities that mammals have that whales also have. To classify a whale as a fish, therefore, is a mistake. Similarly, we might make an idea of gold that only included being a soft metal and gold color. If so, we would be unable to distinguish between gold and fool’s gold. Thus, since it is the mind that makes complex ideas (they are ‘the workmanship of the understanding’), one is free to put together any combination of ideas one wishes and call it what one will. But the product of such work is open to criticism, either on the grounds that it does not conform to already current usage or that it inadequately represents the archetypes that it is supposed to copy in the world. We engage in such criticism in order to improve human understanding of the material world and thus the human condition. This is the convergent character of Locke’s conventionalism. In becoming more accurate, the nominal essence converges on the real essence.