 The resemblance theory faces well-known problems in spelling out the content of resemblance or likeness. For example, a concept is clearly immaterial, and as such radically differs from any material object. Furthermore, there seems to be no formal characteristic of a mental act in virtue of which it can non-trivially be said to resemble anything else. To get around these difficulties, mediaeval philosophers, like the British Empiricists centuries later, appealed to a particular kind of resemblance, namely pictorial resemblance. A portrait of Socrates is about Socrates in virtue of visually resembling Socrates in the right ways. And just as there are pictorial images that are about their subjects, so too are there mental images that are about things. These mental images, whether they are concepts or are contained in concepts, explain the way in which a concept is ‘about’ an object. For an understanding to be about a cat is for it to be or contain a mental image of a cat. The phenomenon of mental ‘aboutness’ is explicated by the more familiar case of pictorial aboutness, itself reduced to a real relation of resemblance.