Confused and Obscure v. Clear and Distinct

Large cat can mean Tabby, lynx or lion 

And therefore where there are supposed two different ideas, marked by two different names, which are not as distinguishable as the sounds that stand for them, there never fails to be confusion; and where any ideas are distinct as the ideas of those two sounds they are marked by, there can be between them no confusion. The way to prevent confusion is to collect and unite into one complex idea, as precisely as is possible, all those ingredients whereby it is differenced from others; and to these ingredients, so united in a determinate number and order, apply steadily the same name.

But this neither accommodating men’s ease or vanity—nor serving any design but that of naked truth, which is not always the thing aimed at—such exactness is rather to be wished than hoped for.

And since the loose application of names, to undetermined, variable, and almost no ideas, serves both to cover our own ignorance, as well as to perplex and confound others, (which goes for learning and superiority in knowledge,) it is no wonder that most men should use it themselves, whilst they complain of it in others.

Though I think no small part of the confusion to be found in the notions of men might, by care and ingenuity, be avoided, yet I am far from concluding it everywhere willful. Some ideas are so complex, and made up of so many parts, that the memory does not easily retain the very same precise combination of simple ideas under one name: much less are we able constantly to divine for what precise complex idea such a name stands in another man’s use of it. From the first of these, follows confusion in a man’s own reasonings and opinions within himself; from the latter, frequent confusion in discoursing and arguing with others.

 —John Locke; An Essay on Human Understanding

Painting: Salvador Dali, Galatea of the Spheres