Where there is mind there is representational opacity, and vice versa. Opacity arises because where there is representation there may be misrepresentation, and the status of the misrepresenting sign or state of the misrepresenting sign-user can only be characterized via the terms used for a correctly represented object. Opacity is not a blight for naturalism, but must be recognized and exploited if naturalism is to adequately embrace the mental. Opacity is illustrated for language, for the mental itself, for depiction and other non-linguistic representation. Alethic modality, a candidate counterexample to the thesis (opacity without mind is defused consequences for our conception of non-human intelligence are outlined.