[1] Upon a reference to the chapter on ‘complex ideas’ (Book II. chap, xii.), it will appear that the term is used in a stricter and a looser sense. In the looser sense it is not confined to _compound_ ideas, but in opposition to simple ones includes those of relation and even ‘abstract general ideas.’ When Locke thinks of the _general_ idea of substance apart from the complication of accidents referred to it, he opposes it to the complex idea, according to the stricter sense of that term. On the other hand, when he thinks of it as ‘made up’ of the idea of _something_ plus that of relation to qualities (as if there could be an idea of something apart from such relation), it seems to him to have two elements, and therefore to be complex. The abstract idea according to Locke at once precedes and follows the complex. 36. In the passage above quoted, our aptness to consider a complication of simple ideas, which we notice to go constantly together, as one simple idea, is accounted for as the result of a presumption that they belong to one thing. This presumption is again described in the words that ‘we accustom ourselves to suppose some substratum, wherein they do subsist, and from which they do result; which therefore we call substance.’ Here it is implied that the idea of substance, _i.e._ ‘the general idea of something related as a support to accidents,’ is one gradually formed upon observation of the regular coincidence of certain simple ideas. In the sequel (sec. 3 of the same chapter I. xxiii.) we are told that such an idea--‘an obscure and relative idea of substance in general--being thus made, we come to have the ideas of particular sorts of substances by collecting such combinations of simple ideas as are, by experience and observation of men’s senses, taken notice of to exist together.’ Thus a _general_ idea of substance having been formed by one gradual process, ideas of particular sorts of substances are formed by another and later one. But then the very same ‘collection of such combinations of simple ideas as are taken notice of to exist together,’ which (according to sec. 3) constitutes the later process and follows upon the formation of the _general_ idea of substance, has been previously described as preceding and conditioning that formation. It is the complication of simple ideas, noticed to go constantly together, that (according to sec. 1) leads to the ‘idea of substance in general.’ To this see-saw between the process preceding and that following the formation of the idea in question must be added the difficulty, that Locke’s account makes the general idea precede the particular, which is against the whole tenor of his doctrine of abstraction as an operation whereby ‘the mind makes the particular ideas, received from particular objects, to become general.’ (Book II. chap. xi. sec. 9.) Reference of ideas to nature or God, the same as reference to substance.