Book II - Chapter XXX Of Real and Fantastical Ideas 1. Ideas considered in reference to their archetypes. Fantastical or chimerical, I call such as have no foundation in nature, nor have any conformity with that reality of being to which they are tacitly referred, as to their archetypes. If we examine the several sorts of ideas before mentioned, we shall find that, 2. Simple ideas are all real appearances of things.
Complex ideas are voluntary combinations.
And to this I say that, 4. Mixed modes and relations, made of consistent ideas, are real. Secondly, Mixed modes and relations, having no other reality but what they have in the minds of men, there is nothing more required to this kind of ideas to make them real, but that they be so framed, that there be a possibility of existing conformable to them. These ideas themselves, being archetypes, cannot differ from their archetypes, and so cannot be chimerical, unless any one will jumble together in them inconsistent ideas. But this fantasticalness relates more to propriety of speech, than reality of ideas.