Wittgenstein himself warned against this blind alley. We approach the mental as if it ought to conform to the physical and then find ourselves in the position of having to deny the obvious. Not that ordinary modes of speech are sacrosanct, but when a denial of the aptness of a common expression brings with it an abnegation of the familiar fact which it is used to describe, we may well suspect we have approached the mental in the wrong way. Wittgenstein offers two correctives. First,he suggests that we treat the mind as sui generis, allowing for a radical dualism close to that of Sartre, in which it would be wrong to think of the mental in terms of physical analogies. Secondly, he points out certain features, or preconditions, of our understanding of mental phenomena which show that it is wrong in any case to regard the inner as an autonomous sphere of mental life, as if, for example, what distinguished a mental image from a so-called exemplary one was its privacy, unmeasurableness, and so on.