89. There are lurking here two opposite views of the relation between the nominal essence and the real thing. According to one view, which prevails in the later chapters of the Second Book and in certain passages of the third, the relation between them is that with which we have already become familiar in the doctrine of substance--that, namely, between ideas as in us and the same as in the thing. (Book II, chap. xxiii. secs. 9 and 10.) No distinction is made between the ‘idea in the mind’ and the ‘actual sensation.’ The ideas in the mind are also in the thing, and thus are called its qualities, though for the most part they are so only secondarily, _i.e._ as effects of other qualities, which, as copied directly in our ideas, are called primary, and relatively to these effects are called powers. These powers have yet innumerable effects to produce in us which they have not yet produced. (Book II. chap. xxxi. sec. 10.) Those which have been so far produced, being gathered up in a complex idea to which a name is annexed, form the ‘nominal essence’ of the thing. Some of them are of primary qualities, more are of secondary. The originals of the former, the powers to produce the latter, together with powers to produce an indefinite multitude more, will constitute the ‘real essence,’ which is thus ‘a standard made by nature,’ to which the nominal essence is opposed merely as the inadequate to the adequate. The ideas, that is to say, which are indicated by the name of a thing, have been really ‘found in it’ or ‘produced by it,’ but are only a part of those that remain to be found in it or produced by it. It is in this sense that Locke opposes the adequacy between nominal and real essence in the case of mixed modes to their perpetual inadequacy in the case of ideas of substances. The combination in the one case is artificially made, in the other is found and being perpetually enlarged. This he illustrates by imagining the processes which led Adam severally to the idea of the mixed mode ‘jealousy’ and that of the substance ‘gold.’ In the former process Adam ‘put ideas together only by his own imagination, not taken from the existence of anything ... the standard there was of his own making.’ In the latter, ‘he has a standard made by nature; and therefore being to represent that to himself by the idea he has of it, even when it is absent, he puts no simple idea into his complex one, but what he has the perception of from the thing itself. He takes care that his idea be conformable to this archetype.’ (Book III. chap. vi. secs. 46, 47.) ‘It is plain,’ however, ‘that the idea made after this fashion by this archetype will be always inadequate.’ ... about real essence in this sense there may be general knowledge.