However, he immediately goes on to assume that the theory must involve Perry's stronger conclusion that the self concept in question would have to characterize its subject uniquely in a neutral language, and objects: ven if Castor were sufficiently narcissistic to associate such self concep with his every use of 'I', his twin, Pollux, whose mental life is qualitatively identical with Castor's, would associate the same self concept with his every (matching) use of 'I'.