U.T. Place's statement that consciousness is a "pattern of brain activity"1 is obviously intended as a theory of psychophysical identity. Yet strictly speaking, and taken for what it literally says, Place's statement does not necessarily imply a true identity theory—at least not if we assume that the identity thesis says more than merely that there is a correlation between mental events and brain processes. For the question remains: Is the "pattern' of the brain activity caused by the specific physical processes in the brain, or on the other hand, does the "pattern' itself perhaps impose itself upon whatever matter it finds existing in the brain, just as a sound wave imposes itself upon whatever medium it passes through? It would be odd indeed to speak of a theory of "sound-wood identity' simply because it is found that the sound is a "pattern of wood activity' when it passes through a wooden medium. Of course, sound cannot occur without a medium; furthermore, it needs an appropriate type of medium—not just any kind of matter is a good conductor of sound. But these facts would not be inconsistent with a denial that sound and wood are identical, any more than a dualist like Aquinas should be considered an identity theorist on the basis that he says mental events cannot be predicated of just any old kind of material substratum. While there is a sense in which the vibration of the wood and the sound are in fact identical as the sound passes through the wood, this type of identity is a weaker one than the identity theorists mean to assert. It remains true that the removal of the wood and substitution of some other medium—for example, air—would fail to alter significantly the pattern of activity which "is' sound. The pattern could therefore exist without this or that particular material medium, though it is true that it needs some material medium. It may also be, then, that this type of identity statement, as applied to the relation between mind and brain, is correspondingly weak. It does not necessarily deny that the consciousness causes the brain activity, for example, which would be a form of epiphenomenalism which reverses the terms from the usual epiphenomenalism that would treat the physical events as the causal agents.