In 1956, twenty-one years after developing his famous thought experiment now known as Schrodinger’s Cat, Erwin Schrodinger was invited to deliver the Tarner Lecture at Cambridge University. His topic was not quantum mechanics, for which he had been awarded a Nobel Prize in 1933 and was considered a luminary. Instead, he delivered a lecture entitled the Physical Basis of Consciousness and explored the question: What kind of material process is directly associated with consciousness?

“It is a special kind of mechanism by which the individual responds to alternative situations by accordingly alternating behavior, a mechanism for adaptation to a changing surrounding. It is the most elaborate and the most ingenious among all such mechanisms, and wherever it turns up it rapidly gains a dominating role.”

At the time, most biologists and physicists continued to dismiss the question of consciousness as one that “cannot be answered and which ought to be left to idle dreamers,” as Schrodinger himself described the perspective of many of his peers in the introduction to his lecture. Still, Schrodinger dove in and presented his tentative answer: Consciousness is an advanced biological mechanism for learning, adaptation, and evolution. Schrodinger concluded his lecture by revealing that he had been contemplating the topic of consciousness for more than thirty years. Perhaps the deeper question for Schrodinger all along was: How conscious is the cat?

“One might say, metaphorically, that consciousness is the tutor who supervises the education of the living substance, but leaves his pupil alone to deal with all those tasks for which he is already sufficiently trained. But I wish to underline three times in red ink that I mean this only as a metaphor. The fact is only this, that new situations and the new responses they prompt are kept in the light of consciousness; old and well practiced ones are no longer so.”

Since then, understanding the nature of consciousness has captured the imaginations of many other scientific luminaries. Advances in medical technology have allowed us to study the nervous system and the brain with greater degrees of precision, and have fueled an expansion of research in neurobiology and psychology. While a detailed understanding and unified definition of consciousness, one that is shared by biologists, psychologists, philosophers and theologians, remains elusive, descriptions of the phenomenon of consciousness are increasingly aligned.