100. The doctrine of primary qualities was naturally the one upon which the criticism of Berkeley and Hume first fastened, as the most obvious aberration from the ‘new way of ideas.’ That the very notion of the senses as ‘reporting’ anything, under secondary no less than under primary qualities, implies the presence of ‘fictions of thought’ in the primitive consciousness, may become clear upon analysis; but it lies on the surface and is avowed by Locke himself (Book II. chap. viii. secs. 2, 7), that the conception of primary qualities is only possible upon distinction being made between ideas as in our minds, and the ‘nature of things existing without us,’ which cannot be given in the simple feeling itself. This admitted, the distinction might either be traced to the presence within intelligent consciousness of another factor than simple ideas, or be accounted for as a gradual ‘invention of the mind.’ In neither way, however, could Locke regard it and yet retain his distinction between fact and fancy, as resting upon that between the nature of things and the mind of man. The way of escape lay in a figure of speech, the figure of the wax or the mirror. ‘The ideas of primary qualities are resemblances of them.’ (Book II. chap, viii. sec. 15.) These qualities then may be treated, according to occasion, either as primitive data of consciousness, or as the essence of that which is the unknown opposite of consciousness--in the latter way when the antithesis between nature and mind is in view, in the former when nature has yet to be represented as knowable. Locke answers that they copy themselves in ideas--Berkeley’s rejoinder. Locke gets out of the difficulty by his doctrine of solidity.