... if the stuff of the universe that we know directly is mind, and matter is the same thing known only by means of conceptual symbols created by mind, it would seem as reasonable to call at least part of reality mind as to call it matter. And matter, even crude matter, is not what it was. It has turned into energy, and the atom has become a pattern and the molecule a pattern of patterns, till all the different physical substances and their behaviour have come to be regarded as the outcome of the structure of their primitive components. But we have already met with pattern in the nervous system, underlying and rendering possible the most fundamental characteristics of the mind. And pattern in some mysterious way possesses a life of its own, for it can survive a change in the identity of its component parts as longs as its structure remains the same. As a wave can move over the sea and remain the same wave, though the water of which it is composed is continuously changing, a pattern can shift over the retina and therefore over the visual area of the brain and remain recognizably the same pattern. The pattern of our personality though it changes slowly remains substantially the same, though every protein molecule in the body, including the nervous system, is changed three times a year. The ingredients have altered but not the structure.

— W. Russell Brain (Mind, Perception and Science) —