And again, among sensations themselves the sensation of a foreign object and that of the special object, or that of a kindred object and that of the object of the sense in question, are not equally authoritative, but in the case of colour, sight, not taste, has the authority, and in the case of flavour, taste, not sight; each of which senses never says at the same moment of the same object that it at the same time is so and not so.