109. To obtain a direct and compendious answer to this question from Locke’s own mouth is not easy, owing to the want of adjustment between the several passages where he treats of the primary qualities. They are originally enumerated as the ‘bulk, figure, number, situation, and motion or rest of the solid parts of bodies’ (Book II. chap. viii. sec. 23), and, as we have seen, are treated as all involved in that idea of solidity which is given in the sensation of touch. We have no further account of them till we come to the chapters on ‘simple modes of space and duration’ (Book II. chaps. xiii. &c.), which are introduced by the remark, that in the previous part of the book simple ideas have been treated ‘rather in the way that they come into the mind than as distinguished from others more compounded.’ As the simple idea, according to Locke, is that which comes first into the mind, the two ways of treatment ought to coincide; but there follows an explanation of the simple modes in question, of which to a critical reader the plain result is that the idea of body, which, according to the imaginary theory of ‘the way that it came into the mind’ is simple and equivalent to the sensation of touch, turns out to be a complex of relations of which the simplest is called space. According to Locke’s account they are relations, and thus inventions of the mind. 110. To know what space itself is, ‘we are sent to our senses’ of sight and touch. It is ‘as needless to go to prove that men perceive by their sight a distance between bodies of different colours, or between the parts of the same body, as that they see colours themselves; nor is it less obvious that they can do so in the dark by feeling and touch.’ (Book II. chap. xiii. sec. 2.) Space being thus explained by reference to distance, and distance _between bodies_, it might be supposed that distance and body were simpler ideas. In the next paragraph, however, distance is itself explained to be a mode of space. It is ‘space considered barely in length between any two beings,’ and is distinguished _(a)_ from ‘capacity’ or ‘space considered in length, breadth, and thickness;’ _(b)_ from ‘figure, which is nothing but the relation which the parts of the termination of extension, or circumscribed space, have among themselves;’ _(c)_ from ‘place, which is the relation of distance between anything and any two or more points which are considered as keeping the same distance one with another, and so as at rest.’ It is then shown at large (Book II. chap. xiii. sec. 11), as against the Cartesians, that extension, which is ‘space in whatsoever manner considered,’ is a ‘distinct idea from body.’ The ground of the distinction plainly lies in the greater complexity of the idea of body. Throughout the definition just given ‘space’ is presupposed as the simpler idea of which capacity, figure, and place are severally modifications; and these again, as ‘primary qualities,’ though with a slight difference