But if, as we have shown above, the very quality itself, in its specific texture, is the suggestion of a certain way of existing put to us, and responded to by us, in so far as we have sensory fields; and if the perception of a colour, endowed with a definite structure (in the way of surface colour or area of colour), at a place or distance away either definite or vague, presupposes our opening on to a reality or a world, how can we possibly dissociate the certainty of our perceptual existence from that of its external counterpart?