Abstract: Brain action is both physically controlled and beyond computational simulation. Accordingly, there is a strong case for examining brain organization in a way that specifically seeks out structures in the brain that might plausibly support such putative non-computational action at the ill-understood borderline between quantum and classical physics. Thus, we must seek out structures in the brain where the actual physics that operates at this level could plausibly have important influence on brain action. This is the basis of the Orch-OR model that Stuart Hameroff and I have been proposing, and which he describes in the foregoing article. The case is strongly put forward that the neuronal microtubules play a key role in the required quantum/classical borderline activities which might have an essential relevance to the phenomenon of consciousness. The exploration of such deeper level of neuronal structure and function is very much a continuation of the line of work so wonderfully initiated by Cajal.