# An Essay Concerning Human Understanding/Book II/Chapter XXX

1. Ideas considered in reference to their archetypes. Besides what we have already mentioned concerning ideas, other considerations belong to them, in reference to things from whence they are taken, or which they may be supposed to represent ; and thus, I think, they may come under a three-fold distinction, and are : –
First, either real or fantastical ;
Secondly, adequate or inadequate ;
Thirdly, true or false.
First, by real ideas, I mean such as have a foundation in nature ; such as have a conformity with the real being and existence of things, or with 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. First, Our simple ideas are all real, all agree to the reality of things : not that they are all of them the images or representations of what does exist ; the contrary whereof, in all but the primary qualities of bodies, hath been already shown. But, though whiteness and coldness are no more in snow than pain is ; yet those ideas of whiteness and coldness, pain, &c., being in us the effects of powers in things without us, ordained by our Maker to produce in us such sensations ; they are real ideas in us, whereby we distinguish the qualities that are really in things themselves. For, these several appearances being designed to be the mark whereby we are to know and distinguish things which we have to do with, our ideas do as well serve us to that purpose, and are as real distinguishing characters, whether they be only constant effects, or else exact resemblances of something in the things themselves : the reality lying in that steady correspondence they have with the distinct constitutions of real beings. But whether they answer to those constitutions, as to causes or patterns, it matters not ; it suffices that they are constantly produced by them. And thus our simple ideas are all real and true, because they answer and agree to those powers of things which produce them in our minds ; that being all that is requisite to make them real, and not fictions at pleasure. For in simple ideas (as has been shown) the mind is wholly confined to the operation of things upon it, and can make to itself no simple idea, more than what it has received.
3. Complex ideas are voluntary combinations. Though the mind be wholly passive in respect of its simple ideas ; yet, I think, we may say it is not so in respect of its complex ideas. For those being combinations of simple ideas put together, and united under one general name, it is plain that the mind of man uses some kind of liberty in forming those complex ideas : how else comes it to pass that one man’s idea of gold, or justice, is different from another’s, but because he has put in, or left out of his, some simple idea which the other has not ? The question then is, Which of these are real, and which barely imaginary combinations ? What collections agree to the reality of things, and what not ? 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. Indeed, as any of them have the names of a known language assigned to them, by which he that has them in his mind would signify them to others, so bare possibility of existing is not enough ; they must have a conformity to the ordinary signification of the name that is given them, that they may not be thought fantastical : as if a man would give the name of justice to that idea which common use calls liberality. But this fantasticalness relates more to propriety of speech, than reality of ideas. For a man to be undisturbed in danger, sedately to consider what is fittest to be done, and to execute it steadily, is a mixed mode, or a complex idea of an action which may exist. But to be undisturbed in danger, without using one’s reason or industry, is what is also possible to be ; and so is as real an idea as the other. Though the first of these, having the name courage given to it, may, in respect of that name, be a right or wrong idea ; but the other, whilst it has not a common received name of any known language assigned to it, is not capable of any deformity, being made with no reference to anything but itself.
5. Complex ideas of substances are real, when they agree with the existence of things. Thirdly, Our complex ideas of substances, being made all of them in reference to things existing without us, and intended to be representations of substances as they really are, are no further real than as they are such combinations of simple ideas as are really united, and co-exist in things without us. On the contrary, those are fantastical which are made up of such collections of simple ideas as were really never united, never were found together in any substance : v.g. a rational creature, consisting of a horse’s head, joined to a body of human shape, or such as the centaurs are described : or, a body yellow, very malleable, fusible, and fixed, but lighter than common water : or an uniform, unorganized body, consisting, as to sense, all of similar parts, with perception and voluntary motion joined to it. Whether such substances as these can possibly exist or no, it is probable we do not know : but be that as it will, these ideas of substances, being made conformable to no pattern existing that we know ; and consisting of such collections of ideas as no substance ever showed us united together, they ought to pass with us for barely imaginary : but much more are those complex ideas so, which contain in them any inconsistency or contradiction of their parts.