What I wish to point out is that we have no reason for supposing that there are such things as mental images at all for supposing that blue is part of the content of the sensation of blue, and that even if there are mental images, no mental image and no sensation or idea is merely a thing of this kind: that 'blue,' even if it is part of the content of the image or sensation or idea of blue, is always also related to it in quite another way, and that this other relation, omitted in the traditional analysis, is the only one which makes the sensation of blue a mental fact at all.