The attainment of consciousness and self-awareness clearly sets mankind apart from other living organisms. Our ability to step outside of ourselves, to introspect, reflect and have a theory of mind is truly wondrous. Many philosophers, theologians and scientists across the ages have attempted to define consciousness, delineate its existence and identify its essence. Greek ‘thinkers’ were perhaps the first to associate their psychological theories with empirical investigations of the body and mind. For instance, in early Greek texts, the part of the body with which man thinks and feels is described using the term ‘phrenes’. The latter originally denoted the lungs and subsequently the diaphragm, and clearly neither forms the seat of reason or emotion as we now understand Reference Ross(1). However, it is likely that philosophers predating Socrates grappled with questions such as the existence of the soul, in particular, what form it took and indeed its nature. In all likelihood, it was Aristotle and his associates who first drew meaningful links between human anatomy and physiology and in particular, the senses of man Reference Ross(1). Herophilus and Erasistratus, Alexandrian biologists of the 3rd Century BC, were the first to detail the structure of the brain, in particular its ventricles, and clearly identify the nervous system distinguishing notably between sensory and motor functions. The theories that emanated from experimentation were on the whole vague and poorly substantiated, and not surprisingly consciousness itself remained elusive.

As a phenomenon, consciousness seems to be self-evident and readily accessible Reference Sperry(2). It nevertheless manages to defy both theoretical understanding and ‘real’ description, and this inability to characterise it successfully perhaps suggests a fundamental misconception – maybe the phenomenon as ‘we’ know it does not exist! The questions this invokes are numerous and perplexing and will continue to engage the best minds for many generations. In this issue, I am grateful to the guest editor for this issue, Professor Perminder Sachdev Reference Sachdev(3), and his esteemed colleagues who have bravely attempted to address aspects of the mind and its functioning. It is for the reader to judge if these papers make it any clearer what purpose consciousness serves or indeed how it relates to mind or matter. Nevertheless, in this issue of Acta Neuropsychiatrica the mind does matter as demonstrated by Lagopoulos Reference Lagopoulos(4) who grapples with the more concrete task of quantifying matter in Brain Bytes and Berk Reference Berk(5) who suggests that exercise is a matter that exercises the mind.