Some years ago, in a Hughlings Jackson lecture, I ventured to give some personal views upon the nature of the relationship of mind to brain. I said nothing original, yet something rather different from what we are accustomed to hear in those popular symposia on the brain-mind relationship, or upon brain mechanisms and consciousness, of which we have had a number of examples in recent years. The views I expressed had the sanction of philosophers from Aristotle to Aquinas, and, in a measure, of such physiological geniuses as Hughlings Jackson and Sherrington, but there is little interest in them at the present time in a scientific world still intensely preoccupied with the concepts of cybernetics and biophysics: preoccupied in the sense that some scientists find they cannot easily entertain any concepts which transcend these fragmentary ideas.

How we approach this problem depends largely upon our concept of nature and of natural science. Therefore, I define natural science as being ‘the study of nature as perceived: a study wherein nature is disclosed as a complex of entities whose mutual relations can be thought of and discussed without reference to sense awareness or thought about it’. This is to say that we can be perfectly good natural scientists without bothering our heads about the nature of perceiving, or the theory of knowledge—epistemology, as it is called. This is a complex definition, which I have taken from a great mathematician and philosopher, Alfred North Whitehead. Its full import will appear later, but in the meantime I wish to point out that nature, that is, the world as perceived, does not comprehend all that the human mind can entertain.